Optical device and imaging device with mechanism for reducing condensation

ABSTRACT

In an optical device, a lens assembly includes a lens for receiving light and a holder for holding the lens. A circuit board performs at least one process based on the received light. A housing has an opening and is configured to house the lens assembly and the circuit board therein such that at least part of the circuit board faces the lens assembly, and the lens assembly is exposed via the opening. A mechanism for defining a passage located around the lens assembly to communicate with the opening. The passage guides air, entering an inside of the housing via the opening, so as not to be directed toward the circuit board.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation Application of U.S. patentapplication Ser. No. 14/641,726, filed on Mar. 9, 2015. Theseapplications claim the benefit and priority of Japanese PatentApplications No. 2014-46453 and 2014-260494 respectively, filed on Mar.10, 2014 and Dec. 24, 2014. The entire disclosures of each of the aboveapplications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to optical devices and imaging deviceseach equipped with a lens assembly, a circuit board, and a housing thathouses the lens assembly and circuit board.

BACKGROUND

There are imaging devices, which are an example of optical devices,equipped with a lens assembly comprised of a lens and a holder forholding the lens, a circuit board, and a housing that houses the lensassembly and circuit board. In such an imaging device, the occurrence ofcondensation on the circuit board may cause water droplets to producewater migration in the circuit board, resulting in insulation failuresin the circuit board.

There are some methods for reducing the risk of the occurrence ofcondensation on the circuit board. A first method is to coat adrip-proof material on the circuit board, and a second method is toencapsulate a drying agent or inert gas in the housing. A third methodis to design the housing having a closable passage communicating betweenthe inside and outside of the housing, and fit a moisture permeablematerial impervious to water in the closable passage. The second andthird methods are disclosed respectively in Japanese Patent ApplicationPublications No. 2002-221748 and 2008-239017.

SUMMARY

However, the first method may increase the manufacturing cost of theimaging device for the drop-proof material, and require coating workusing the drop-proof material. The second method may result in heatgenerated from the circuit board being excessively trapped in theencapsulated housing. The third method may increase the manufacturingcost of the imaging device for the specific design of the housing andfor the moisture permeable material.

In view the circumstances set forth above, one aspect of the presentdisclosure seeks to provide optical devices and imaging devices, each ofwhich includes a lens assembly, a circuit board, and a housing thathouses the lens assembly and circuit board, each of which is capable ofaddressing the problems set forth above.

Specifically, an alternative aspect of the present disclosure aims toprovide such optical devices and imaging devices, each of which has asimpler structure for reducing the risk of condensation occurring on thecircuit board, without sealing the housing.

According to a first exemplary aspect of the present disclosure, thereis provided an optical device. The optical device includes a lensassembly including at least one lens for receiving light and a holderfor holding the at least one lens. The optical device includes a circuitboard for performing at least one process based on the received light.The optical device includes a housing having an opening and configuredto house the lens assembly and the circuit board therein such that atleast part of the circuit board faces the lens assembly, and the lensassembly is exposed via the opening. The optical device includes amechanism defining a passage located around the lens assembly tocommunicate with the opening. The passage guides air, entering an insideof the housing via the opening, so as not to be directed toward thecircuit board.

According to a second exemplary aspect of the present disclosure, thereis provided an optical system for a vehicle. The optical system includesthe optical device as recited in the first exemplary aspect. The housinghas a concave recess communicating with the opening thereof. The opticaldevice is housed in the housing with the lens assembly being exposed viaa set of the concave recess and the opening such that a field of view ofthe lens assembly is ensured via the set of the concave recess and theopening. The optical system includes a cover having an opening wall andcovering the optical device, and a bracket attached to an inner surfaceof a windshield of the vehicle and to the cover. The bracket covers theopening wall of the cover such that the field of view of the lensassembly is ensured via the set of the concave recess and the opening.The optical system includes a hood at least partly fitted in the concaverecess with the field of view of the lens assembly being unobscured.

According to a third exemplary aspect of the present disclosure, thereis provided an imaging device to be installed in a vehicle. The imagingdevice includes a lens assembly including at least one lens forreceiving light and a holder for holding the at least one lens, animaging sensor for successively picking up images based on the receivedlight, and a circuit board. The imaging device includes an imageprocessing circuit implemented in the circuit board and configured tocapture the images successively picked-up images, and perform imageprocessing of each of the picked-up images. The image processing circuitincludes 3.3 V signal lines, and external terminals with 1.27 mm orlower pitches. The image processing circuit is configured to receive,via a serial interactive communication bus installed in the vehicle, asignal output from at least one sensor installed in the vehicle. Thesignal is indicative of a travelling condition of the vehicle. The imageprocessing circuit is configured to output, based on at least one of aresult of the image processing of the image processing circuit and thesignal output from the at least one sensor, a control signal to thevehicle via the serial interactive communication bus. The control signalcontrols at least one actuator installed in the vehicle. The imagingdevice includes a housing having an opening and configured to house thelens assembly, the circuit board, and the imaging sensor therein suchthat at least part of the circuit board faces the lens assembly, and thelens assembly is exposed via the opening. The imaging device includes amechanism defining a passage located around the lens assembly tocommunicate with the opening, the passage guiding air, entering aninside of the housing via the opening, so as not to be directed towardthe circuit board.

According to a fourth exemplary aspect of the present disclosure, thereis provided an optical system. The optical system includes a lensassembly including at least one lens for receiving light and a holderfor holding the at least one lens, and a circuit board for performing atleast one process based on the received light. The optical systemincludes a housing having an opening and configured to house the lensassembly and the circuit board therein such that at least part of thecircuit board faces the lens assembly, and the lens assembly is exposedvia the opening. The optical system includes a mechanism defining apassage located around the lens assembly to communicate with theopening. The passage guides air, entering an inside of the housing viathe opening, so as not to be directed toward the circuit board. Theoptical system includes a bracket attached to a windshield of a vehicleand configured to fix the lens assembly to the windshield. The opticalsystem includes a hood attached to the bracket and surrounding a fieldof view of the lens assembly for reducing a possibility that an objectlocated outside of the field of view of the lens assembly is captured bythe field of view of the lens assembly.

Each of the optical device, optical system, imaging device, and theoptical system according to the respective first, second, third, andfourth exemplary aspects includes the mechanism. The mechanism definesthe passage located around the lens assembly to communicate with theopening. The passage guides air, entering the inside of the housing viathe opening, so as not to be directed toward the circuit board.

This mechanism therefore reduces the possibility that the air enteringthe inside of the housing hits the circuit board because the air isdirected to be departed from the circuit board. Particularly, even ifthe air, which has been directed to be departed from the circuit board,finally hits the circuit board, the air has travelled a long distanceuntil hitting the circuit board. This is because the air was directed tobe departed from the circuit board once. This results in the air, whichhas travelled such a long distance, being sufficiently cooled whenreaching the circuit board. This reduces the risk of the occurrence ofcondensation on the circuit board without sealing the housing.

The above and/or other features, and/or advantages of various aspects ofthe present disclosure will be further appreciated in view of thefollowing description in conjunction with the accompanying drawings.Various aspects of the present disclosure can include and/or excludedifferent features, and/or advantages where applicable. In addition,various aspects of the present disclosure can combine one or morefeature of other embodiments where applicable. The descriptions offeatures, and/or advantages of particular embodiments should not beconstrued as limiting other embodiments or the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects of the present disclosure will become apparent from thefollowing description of embodiments with reference to the accompanyingdrawings in which:

FIG. 1 is a perspective view schematically illustrating an example ofthe appearance of an imaging device according to an embodiment of thepresent disclosure;

FIG. 2 is a plan view of the imaging device illustrated in FIG. 1;

FIG. 3 is an exploded perspective view of the imaging device illustratedin FIG. 1;

FIG. 4 is a cross sectional view schematically illustrating a camerasystem including the imaging device and attached to a front windshieldof a vehicle;

FIG. 5 is an exploded perspective view schematically illustrating thecamera system illustrated in FIG. 4;

FIG. 6 is a block diagram schematically illustrating an example of apart of a functional structure of the vehicle including an example ofthe functional structure of the camera system;

FIG. 7 is a view schematically illustrating a part of an imageprocessing circuit implemented on a control circuit board of the imagingdevice;

FIG. 8 is a block diagram schematically illustrating an example of thefunctional structure of the image processing circuit illustrated in FIG.7;

FIG. 9 is a perspective view of a camera module of the imaging deviceillustrated in FIG. 1;

FIG. 10 is an exploded perspective view of the camera module illustratedin FIG. 9;

FIG. 11 is a perspective view schematically illustrating the inside of ahousing illustrated in FIG. 1 before the camera module is installed inthe housing;

FIG. 12 is a perspective view schematically illustrating the inside ofthe housing illustrated in FIG. 1 after the camera module is installedin the housing;

FIG. 13 is a cross sectional view taken along line XIII-XIII of FIG. 2;

FIG. 14 is a cross sectional view taken along line XIV-XIV of each ofFIGS. 2 and 13; and

FIG. 15 is a cross sectional view of an imaging device according to anexample of a first modification of the embodiment, which corresponds tothe sectional view illustrated in FIG. 13.

DETAILED DESCRIPTION OF EMBODIMENT

An embodiment of the present disclosure will be described hereinafterwith reference to the accompanying drawings.

An imaging device 1, which is an example of optical devices, accordingto the embodiment is installed in, for example, a vehicle V, a part,such as a front windshield, of which is illustrated in FIG. 4. Theimaging device 1 picks up images of a region ahead of the vehicle V. Theimaging device 1 also performs analyses on the picked-up images, andsends the results of analyses to one or more ECUs, such as headlightcontrol ECU and a lane departure detection ECU, installed in the vehicleV.

In the specification, the front, rear, right, and left directionsdescribed show the front, rear, right, and left directions of thevehicle V when the vehicle V is travelling in the front direction of thevehicle V. The front-rear direction corresponds to the longitudinaldirection of the vehicle V, and the right-left direction corresponds tothe lateral direction, i.e. the width direction, of the vehicle V.

Referring to FIGS. 1 and 2, the imaging device 1 is comprised of ahousing 2 and a camera module 3 installed in the housing 2. The housing2 is made of, for example, a metal, and has a substantially rectangularparallelepiped shape with an inner hollow container space. The housing 2has a rear wall 2 a directed to the rear side of the vehicle V when theimaging device 2 is installed in the vehicle V.

The housing 2 has a top wall 2 b inclined toward the front side of thevehicle V. A rectangular part of a rear half portion of the top wall 2 bis protruded upward to form a protruded wall 25; the protruded wall 25is located to be slightly shifted rightward relative to the middle ofthe rear half portion in the lateral direction of the housing 2.

The protruded wall 25 serves as an attachment wall to, for example, thefront windshield 102 of the vehicle V described later (see FIG. 4).Hereinafter, the protruded wall 25 will be referred to as an attachmentwall 25.

The attachment wall 25 has a substantially U-shaped concave recess 21 aformed in a front surface 25S thereof to a substantially center of theattachment wall 25, so that a top surface of the attachment wall 25 hasa substantially concave shape. In other words, the attachment wall 25 iscomprised of a left-hand end 26 and a right-hand end 27 that sandwichesthe U-shaped concave recess 21 a.

The housing 2 has a trapezoidal concave recess 22 formed in the topsurface 2 b downward. The trapezoidal concave recess 22 has a verticalwall 22 a located close to the front surface 25 s of the attachment wall25. The vertical wall 22 a has a top surface 22 b intersecting with thefront surface 25 s of the attachment wall 25, so that the vertical wall22 a and the attachment wall 25 constitute a downward stepped portion.The vertical wall 22 a has a concave recess 22 c formed in the topsurface 22 b and communicating with the U-shaped concave recess 21 a.The U-shaped concave recess 21 a and the concave recess 22 c constitutean opening 21 for communicating between the exterior and interior of thehousing 2.

The trapezoidal concave recess 22 has a bottom surface 22 d having asubstantially trapezoidal shape. The trapezoidal bottom surface 22 dextends, from the vertical wall 22 a, in the front direction such thatthe extending lower base of the trapezoidal bottom surface 22 d islonger than the upper base thereof.

The opening 21 consisting of the U-shaped concave recess 21 a and theconcave recess 22 c, and the trapezoidal concave recess 22 serve as anexposing structure (21, 22) that causes a part of a lens assembly 3A ofthe camera module 3 installed in the housing 2 to be exposed from thehousing 2, i.e. uncovered. This permits the lens assembly 3A to receivelight from the front of the vehicle V, and the camera module 3 to pickup images ahead of the vehicle V based on the received light. In otherwords, the exposing structure (21, 22) permits the housing 2 not tointerfere with the field of view of the lens assembly 3A, i.e. thecamera module 3.

Referring to FIG. 3, the imaging device 1 is also comprised of a controlcircuit board 4, an electrical connection harness 5, and a bottom cover6. The camera module 3 is disposed above the control circuit board 4 andthe electrical connection harness 5 such that the opening 21 faces thecontrol circuit board 4. The electrical connection harness 5electrically connects electrical parts of the camera module 3 and thecontrol circuit board 4. The bottom cover 6 is disposed at a lower sideof the control circuit board 4 so as to be integral with a bottom wallof the housing 2.

The imaging device 1 constitutes a camera system 100 serving as anexample of imaging apparatuses attached to the vehicle V. The camerasystem 100 is for example attached to the top center of the innersurface of the front windshield 102 of the vehicle V. In other words,the camera system 100 is located to be close to a rearview mirror of thevehicle V.

The camera system 100 includes a plate-like bracket 8, a hood 9, a firstthermal-conductive member 114, a second thermal-conductive member 115, adesign cover 7, a ventilation fan 117, and a hot wire 118 in addition tothe imaging device 1. FIGS. 4 and 5 schematically illustrate a part ofthe front windshield 102. In FIG. 5, the ventilation fan 117 and hotwire 118 are eliminated in illustration for simpler description of thecamera system 100.

Referring to FIGS. 4 and 5, the design cover 7 has arectangular-parallelepiped shape with an inner hollow container thereinand an opening top wall. The imaging device 1 is contained in the innerhollow container of the design cover 7 such that the bracket 8 coversthe top of the imaging device 1 while the hood 9 covers the trapezoidalconcave recess 22.

The bracket 8 is attached via the second thermal-conductive member 115to the top center of the inner surface of the front windshield 102located close to the rearview mirror, more specifically located behindthe rearview mirror.

Specifically, the bracket 8 has an opening 8 a facing at least part ofthe top surface of the attachment wall 25 of the housing 2. The bracket8 also has a substantially V-shaped recess, in other words, notch, 8 bcommunicating with the opening 8 a and facing the trapezoidal concaverecess 22 of the housing 2; the opening 8 a and the V-shaped recess 8 bresult in the bracket 8 having a substantially U shape. The bracket 8serves to fix the housing 2 of the imaging device 1 to the inner surfaceof the front windshield 102. Specifically, the bracket 8 has a firstmajor surface, i.e. a top surface, 8 c fixedly mounted, for example,adhered, on the inner surface of the front windshield 102 via the secondthermal-conductive member 115. The housing 2 is attached to the bracket8 fixedly mounted on the inner surface of the front windshield 102 suchthat the attachment wall 25 of the housing 2 faces the front windshield102 via the first thermally-conductive member 114.

When the housing 2 is attached to the bracket 8, the V-shaped recess 8 bis located in front of the camera module 3. The V-shaped recess 8 b hasa substantially trapezoidal shape so as to become broader in widthtoward the front side of the camera module 3; the recess 8 b correspondsin shape to a horizontally sector imaging region, i.e. a horizontalview-angle region, of the lens assembly 3A of the camera module 3extending in front of the lens assembly 3A. This permits the field ofview of the lens assembly 3A, i.e. the camera module 3, to besufficiently ensured.

The hood 9 is made of a resin, and has a substantially trapezoidalbottom surface, and a pair of opposing side surfaces perpendicular torespective oblique sides of the trapezoidal bottom surface. The hood 9is attached to a lower side of the bracket 8 with the trapezoidal bottomsurface facing the recess 8 b. Specifically, when the housing 2 isattached to the bracket 8, the hood 9 is mounted on or above thetrapezoidal bottom surface 22 d of the trapezoidal concave recess 22such that the bottom surface and the opposing side surfaces of the hood9 surround the substantially sector imaging region (horizontalview-angle region) of the camera module 3; the imaging regionsubstantially corresponds to the field of view of the lens assembly 3AThis reduces the possibility that objects located outside of the sectorimaging region of the camera module 3 are captured by the camera module3.

The first thermal-conductive member 114 is designed as a seat membermade of, for example, a silicone material having a thermal conductivityfrom 1 to 50 [W/m·K] inclusive. The first theiiiial-conductive member114 is located between the attachment wall 25 of the housing 2 and thefront windshield 102 via the opening 8 a. For example, in theembodiment, the first thermal-conductive member 114 is adhered on thetop surface of the attachment wall 25. Thereafter, the firstthermal-conductive member 114 is fixed to the inner surface of the frontwindshield 102 via the second thermal-conductive member 115 while thefirst thermal-conductive member 114 and/or a top portion of theattachment wall 25 is fitted or placed in the opening 8 a of the bracket8. This results in the first thermal-conductive member 114 being adheredon the inner surface of the front windshield 102.

The first thermal-conductive member 114 has a shape and an areasubstantially identical to the shape and area of the top surface of theattachment wall 25. Specifically, the first thermal-conductive member114 has a substantially concave shape and is fixedly mounted on regions25 b of the respective left-hand and right-hand ends 26 and 27 of theattachment wall 25 located both sides of the U-shaped concave recess 21a. The first thermal-conductive member 114 is also fixedly mounted on aregion 25 a of the concave top surface of the attachment wall 25 locatedbehind the U-shaped concave recess 21 a.

The second thermal-conductive member 115 is designed as a seat membermade of, for example, the same material as the material of the firstthermal-conductive member 114. The second thermal-conductive layer 115is disposed between the top surface 8 c of the bracket 8 and the innersurface of the front windshield 102 so as to be fixedly mounted on boththe top surface 8 c of the bracket 8 and the inner surface of the frontwindshield 102.

The second thermal-conductive member 115 has a shape and an areasubstantially identical to the shape and area of the top surface 8 c ofthe bracket 8. Specifically, the second thermal-conductive member 115has an opening 115 a facing the opening 8 a of the bracket 8, and asubstantially V-shaped recess 115 b communicating with the opening 115 aand facing the V-shaped recess 8 b of the bracket 8; the opening 115 aand the V-shaped recess 115 b result in the second thermal-conductivemember 115 has a substantially U shape.

The second thermal-conductive member 115 is adhered on the whole of thetop surface 8 c of the bracket 8 and on the inner surface of the frontwindshield 102 while the opening 115 a and recess 115 b are aligned withthe respective opening 8 a and recess 8 b. For example, the secondthermal-conductive member 115 is attached on both the whole of the topsurface 8 c of the bracket 8 and the inner surface of the frontwindshield 102 with adhesives.

In the embodiment, in order to reduce external visual recognition of theadhesive between the second thermal-conductive member 115 and the innersurface of the front windshield 102, the second thermal-conductivemember 115 is adhered on a black ceramic sheet 103 having an area largerthan the area of the second thermal-conductive member 115. Thereafter,the black ceramic sheet 103 is closely contacted on the inner surface ofthe front windshield 102. The black ceramic sheet 103 has a transparentopening 103 a facing the V-shaped recess 115 b of the secondthermal-conductive member 115. The transparent opening 103 a preventsthe black ceramic sheet 103 from blocking the sector imaging region ofthe camera module 3.

The design cover 7 covers the bracket 8 and the hood 9 from the lowerdirection of them in addition to the imaging device 1 to reduce thepossibility of the bracket 8 and hood 9 being visible from the inside ofthe vehicle V. The design cover 7 has a through hole 7 a formed througha bottom wall; the ventilation fan 117 is fitted in the through hole 7 a(see FIG. 4). The ventilation fan 117 ventilates the compartment of thevehicle V.

The hot wire 118 is designed as, for example a single copper wire havingboth ends connected to a power supply source (not shown) installed inthe vehicle V, and the hot wire 118 generates heat when energized by thepower supply source. For example, the hot wire 118 has a bent portion118 a shaped like a letter S, and is arranged on an inner surface of theblack ceramic sheet 103 such that the S-shaped bent portion 118 a islocated on the inner side of the trapezoidal opening 103 a.Specifically, the S-shaped bent portion 118 a has substantially threelinear portions and two corners joining between the three linearportions to form the substantially S shape. The S-shaped bent portion118 a is located on the trapezoidal opening 103 a while the three linearportions pass through the trapezoidal opening 103 a in the lateraldirection of the black ceramic sheet 103. This permits the front sidespace of the lens assembly 3A of the camera module 3 located below thetrapezoidal opening 103 a to be efficiently heated.

Next, electrical functions of the camera system 100 will be describedhereinafter with reference to FIG. 6. FIG. 6 schematically illustrate anexample of a part of the functional structure of the vehicle V includingan example of the functional structure of the camera system 100. In FIG.6, electrical components of the imaging device 1 only are illustratedwhile other mechanical elements of the imaging device 1, such as thebracket 8 and hood 9, are eliminated in illustration.

Referring to FIG. 6, the vehicle V includes an environment monitoringmodule 75, a sensor module 76, a vehicle control module 77, an HMI(Human Machine Interface) module 78, and a common serial interactivecommunication bus 74 with which the modules 75 to 78 are communicablycoupled.

The environment monitoring module 75 is equipped with, for example, theimaging device 1 and a radar device 752, which serve as devices formonitoring the environmental situations around the vehicle V. Theenvironment monitoring module 75 can include, for example, a rightside-view camera, a left side-view camera, and a rear-view camera. Theright side-view camera is for example attached to the right side-viewmirror of the vehicle V for picking up images of right-hand views fromthe vehicle V. The left side-view camera is for example attached to theleft side-view mirror for picking up images of left-hand views from thevehicle V. The rear-view camera is for example attached to the rearbumper of the vehicle V for picking up rear views from the vehicle V.

The imaging device 1 functionally includes an image sensor 33 a, animage processing circuit 79, and an input/output (I/O) circuit 80described in detail later.

The radar device 752 is operative to transmit probing waves, such asradar waves or laser waves to a predetermined scan region, and receiveechoes from at least one object based on the transmitted probing waves.Based on the received echoes, the radar device 752 is operative togenerate object information including at least

(1) The distance of the at least one object relative to the vehicle V

(2) The relative speed of the at least one object with respect to thevehicle V if the at least one object is a moving object

(3) The lateral position of the at least one object relative to thevehicle V in the lateral direction of the vehicle V.

The radar device 752 can include a sonar for transmitting ultrasonicwaves as the probing waves and for receiving echoes based on theultrasonic waves from at least one object.

The sensor module 76 is operative to measure the operating conditions,i.e. travelling conditions, of the vehicle V. Specifically, the sensormodule 76 includes a vehicle speed sensor 761, an acceleration sensor762, a yaw-rate sensor 763, and so on.

The vehicle speed sensor 761 is operative to measure the speed of thevehicle V, and operative to output, to the bus 74, a sensor signalindicative of the measured speed of the vehicle V.

The acceleration sensor 762 is operative to measure acceleration, forexample, lateral acceleration, of the vehicle V in the vehicle widthdirection, and output, to the bus 74, a sensor signal indicative of themeasured acceleration of the vehicle V.

The yaw-rate sensor 763 is operative to output, to the bus 74, a sensorsignal indicative of an angular velocity around a vertical axis of thevehicle V as a yaw rate of the vehicle V.

That is, the sensor signals sent from the respective sensors 761, 762,and 763 are output to the vehicle control module 77 and the imageprocessing circuit 79 of the environment monitoring module 75 via thebus 74. The sensor signals sent from the respective sensors 761, 762,and 763 can be input to ECUs installed in the vehicle V, such as anengine ECU. The ECUs can be operative to execute various tasks based onthe input sensor signals, and output the executed results of the varioustasks to the bus 74. At that time, the vehicle control module 77 and theimage processing circuit 79 can receive the executed results of thevarious tasks via the bus 74.

The vehicle control module 77 is operative to control actuators includedin target devices installed in the vehicle V, and is operative tocontrol each of the actuators, thus controlling a corresponding one ofthe target devices based on the sensor signals sent from the respectivesensors 761, 762, and 763. The target devices to be controlled includeat least three types of devices included in a body system, a power-trainsystem, and a chassis system of the vehicle V.

For example, the target devices include a steering device 771, a brake772, a motive power generator 773, an automotive transmission 774,headlights 775, directional indicators 776, and windshield wipers 777.

The steering device 771 is operative to assist the driver's steering ofthe steering wheel of the vehicle V. The brake 772 is operative to slowdown the vehicle V. The motive power generator 773 consists of, forexample, an internal combustion engine and/or a motor, and is operativeto generate motive power for travelling the vehicle V. The automotivetransmission 774 is operative to convert a rotational speed and torqueas the motive power generated by the motive power generator 773 into anadjusted rotational speed and adjusted torque, and supply the adjustedrotational speed and adjusted torque to driving wheels of the vehicle V.

The headlights 775 are operative to light up the road on which thevehicle V is travelling. Each of the directional indicators 776 isoperative to flash when the vehicle V is about to turn in acorresponding direction, i.e. right or left, or to make a correspondinglane change. The windshield wipers 777 are operative to clean therespective front windshield 102 and rear windshield from rain, snow, orother moisture.

Note that the vehicle control module 77 includes ECUs 778 forcontrolling actuators installed in the vehicle V; the ECUs 778 includethe headlight control ECU 778 a and the lane departure detection ECU 778b.

The HMI module 78 is operative to provide interfaces between occupantsin the vehicle V and the vehicle V. For example, the HMI module 78includes a buzzer 781, a speaker 782, at least one indicator 783, atleast one display 784, and actuators of the respective devices 781 to784 installed in the vehicle V. The buzzer 781 is operative to output awarning sound, and the speaker 782 is operative to output audibleinformation. The indicator 783 is operative to generating a lightsignal, and the at least one display 784 includes a navigation displayand/or a head-up display installed in a center console of the vehicle V.

In addition, the HMI module 78 can include at least one vibration deviceand at least one reaction force generator (not shown). The at least onevibration device is comprised of a motor for generating vibrations of atleast one of the steering wheel of the vehicle V and one or more seatsof the vehicle V. The at least one reaction force generator is operativeto generate reaction force to be supplied to at least one of thesteering wheel of the vehicle V and a brake pedal of the vehicle V.

Specifically, the HMI module 78 is operative to activate at least one ofthese devices included therein to offer information to occupants of thevehicle V.

The HMI module 78 can include an adjusting unit that allows an occupantto input a desired level of recognition for a recognition task describedlater and/or a timing to start a determining task described later, thustransferring information from an occupant to the vehicle V.

The I/O circuit 80 is designed as a circuit included in various circuitsimplemented on and/or in the control circuit board 4, and operative toallow communications among the various circuits implemented in and/or onthe control circuit board 4.

The image processing circuit 79 is designed as a circuit, such as an ICchip, included in the various circuits implemented on and/or in thecontrol circuit board 4. The image processing circuit 79 is operative toperform the recognition task to recognize the environmental conditionsaround the vehicle V based on images picked up by the imaging device 1and/or the other cameras and the object information measured by and sentfrom the radar device 752.

The image processing circuit 79 is composed of, for example, anelectronic circuit device, which contains 3.3 V signal lines, and isdriven based on 3.3 V. For this reason, the image processing circuit 79has lower power consumption and a lower heating value. Referring to FIG.7, the image processing circuit 79 has for example external terminals 79a with 1.27 mm or lower pitches. This configuration of the imageprocessing circuit 79 contributes to reduction of the image processingcircuit 79 and the control circuit board 4 in size. Note that, asillustrated in FIG. 4, if the image processing circuit 79 consists of asingle device, i.e. a single IC chip, the device preferably has externalterminals with 1.27 mm or lower pitches. However, if the imageprocessing circuit 79 consists of a plurality of devices, i.e. IC chips,at least one of the devices preferably has external terminals with 1.27mm or lower pitches.

Referring to FIG. 8, the image processing circuit 79 successively, i.e.cyclically, captures images successively picked up by the image sensor33 a of the camera module 3, and performs, for each of the capturedimages, a detection task 40 a, a light-source recognition task 40 b, anda lane-marker position detection task 40 c as examples ofimage-recognition tasks.

The image processing circuit 79 performs the detection task 40 a thatdetermines whether there is at least one light source of a vehicleappearing in each of the captured images. Specifically, the imageprocessing circuit 79 determines that there is at least one light sourceof a vehicle appearing in a currently captured image; the at least oneregion has at least one of

(1) An average pixel value equal to or higher than a threshold pixelvalue

(2) A shape similar to one of previously prepared shape patterns

(3) An average color is similar to one of previously prepared colorpatterns.

When it is determined that there is at least one light source appearingin a currently captured image, the image processing circuit 79identifies a position of the at least one light source on the currentlycaptured image as coordinates on the currently captured image.

Next, the image processing circuit 79 performs the light-sourcerecognition task 40 b that determines whether the at least one lightsource is a light source, i.e. a tail lamp, of a preceding vehicle or alight source, i.e. a head lamp, of an oncoming vehicle using, forexample, one of known methods. For example, the light-source recognitiontask 40 b is designed to determine that the at least one light source isa light source of an oncoming vehicle when the average color of the atleast one light source is within a predetermined color range similar towhite. Otherwise, the light-source recognition task 40 b is designed todetermine that the at least one light source is a light source of apreceding vehicle when the average color of the at least one lightsource is within a predetermined color range similar to red. Thus, thelight-source recognition task obtains information indicative of whetherthe at least one light source is a light source of a preceding vehicleor an oncoming vehicle.

Then, the image processing circuit 79 outputs, to the headlight controlECU 778 a via the bus 74, the coordinates of the at least one lightsource appearing in a currently captured image and the obtainedinformation as camera information in the form of signals. The camerainformation represents an example of the results of one or moreimage-recognition tasks.

Note that the image processing circuit 79 is not limited to outputtingcamera information each time it is determined that there is at least onelight source of a vehicle appearing in a currently captured image.Specifically, the image processing circuit 79 can be configured todetermine whether the image processing circuit 79 should output camerainformation to the headlight control ECU 778 a based on informationincluded in the sensor signals sent from the respective sensors 761,762, and 763. The image processing circuit 79 can be configured tooutput camera information to the headlight control ECU 778 a when it isdetei mined that the image processing circuit 79 should output camerainformation to the headlight control ECU 778 a. Otherwise, the imageprocessing circuit 79 can be configured not to output camera informationto the headlight ECU 778 a when it is detei mined that the imageprocessing circuit 79 should not output camera information to theheadlight control ECU 778 a.

The information used by the determination of whether the imageprocessing circuit 79 should output camera information to the headlightcontrol ECU 778 a is included in the sensor signals sent from therespective sensors 761, 762, and 763 to the bus 74, which is referred toas vehicle sensor information, but the present disclosure is not limitedthereto. Specifically, the sensor signals sent from the respectivesensors 761, 762, and 763 via the bus 74 can be processed by anotherECU, and thereafter, the processed sensor signals can be output to theimage processing circuit 79. Then, the image processing circuit 79 uses,as the vehicle sensor information, information included in the processedsensor signals.

Specifically, the image processing circuit 79 obtains, from the vehiclesensor information, values of vehicle behavior parameters, such as thespeed of the vehicle V, the acceleration of the vehicle V, and theyaw-rate of the vehicle V. Then, the image processing circuit 79determines whether the obtained values of the vehicle behaviorparameters are within respective first threshold ranges. Specifically,the image processing circuit 79 determines whether

(1) The obtained value of the vehicle speed is equal to or lower than apredetermined first threshold speed

(2) An absolute value of the obtained acceleration is equal to or lowerthan a predetermined first threshold value

(3) The obtained value of the yaw-rate is equal to or lower than apredetermined first threshold rate.

Let us consider a first case where the obtained values of the vehiclebehavior parameters are beyond the respective first threshold ranges. Inother words, let us consider a first case where the obtained value ofthe vehicle speed is higher than the first threshold speed, the absolutevalue of the obtained acceleration is higher than the first thresholdvalue, and the obtained value of the yaw-rate is higher than the firstthreshold rate.

In the first case, the image processing circuit 79 determines that theimage processing circuit 79 should output camera infoi illation to theheadlight control ECU 778 a.

Otherwise, let us consider a second case where the obtained values ofthe vehicle behavior parameters are within the respective firstthreshold ranges. In other words, let us consider a second case wherethe obtained value of the vehicle speed is equal to or lower than thefirst threshold speed, the absolute value of the obtained accelerationis equal to or lower than the first threshold value, and the obtainedvalue of the yaw-rate is higher than the first threshold rate. In thesecond case, the image processing circuit 79 determines that the imageprocessing circuit 79 should not output camera information to theheadlight control ECU 778 a.

When receiving the camera information sent from the image processingcircuit 79 and the sensor signals sent from the respective sensors 761to 763, the headlight control ECU 778 a is configured to

(1) Send, to first actuators of the respective headlights via the bus74, control signals for changing the beams of light output from therespective headlights 775 between high and low beams

(2) Send, to second actuators of the respective headlights via the bus74, control signals for swiveling the axes of the beams of light outputfrom the respective headlights 775 in the lateral direction of thevehicle V.

As described above, the headlight control ECU 778 a uses the camerainformation for controlling the first and second actuators. In otherwords, the camera information serves as signals to control the first andsecond actuators.

In addition, the image processing circuit 79 performs, as thelane-marker detection task 40 c, a known lane-marker detection task foreach of the captured images. For example, the image processing circuit79 detects, for each of the captured images, positions of lane markerspainted on the road ahead of the vehicle V on which the vehicle V istravelling using a binarizing process of a corresponding one of thecaptured images and a Hough transformation process. Then, the imageprocessing circuit 79 outputs, to the lane departure detection ECU 778 bvia the bus 74, the positions of the lane markers as lane-markerposition information.

Note that the image processing circuit 79 is not limited to outputtinglane-marker position information each time the image processing circuit79 captures an image output from the image sensor 33 a.

Specifically, the image processing circuit 79 can be configured todetermine whether the image processing circuit 79 should outputlane-marker position information to the lane departure detection ECU 778b based on the vehicle sensor information included in the sensor signalssent from the respective sensors 761, 762, and 763. The image processingcircuit 79 can be configured to output lane-marker position informationto the lane departure detection ECU 778 b when it is determined that theimage processing circuit 79 should output lane-marker positioninformation the lane departure detection ECU 778 b. Otherwise, the imageprocessing circuit 79 can be configured not to output lane-markerdetection information to the lane departure detection ECU 778 b when itis determined that the image processing circuit 79 should not outputlane-marker detection information to the lane departure detection ECU778 b.

The vehicle sensor information used by the determination of whether theimage processing circuit 79 should output lane-marker detectioninformation to the lane departure detection ECU 778 b is included in thesensor signals sent from the respective sensors 761, 762, and 763 to thebus 74, but the present disclosure is not limited thereto. Specifically,the sensor signals sent from the respective sensors 761, 762, and 763via the bus 74 can be processed by another ECU, and thereafter, theprocessed sensor signals can be output sent to the headlight ECU 778 a.Then, the image processing circuit 79 uses, as the vehicle sensorinformation, information included in the processed sensor signals.

Specifically, the image processing circuit 79 obtains, from the vehiclesensor information, values of the vehicle behavior parameters, such asthe speed of the vehicle V, the acceleration of the vehicle V, and theyaw-rate of the vehicle V. Then, the image processing circuit 79determines whether the obtained values of the vehicle behaviorparameters are within respective second threshold ranges that can beequal to or different from the respective first threshold ranges.Specifically, the image processing circuit 79 determines whether

(1) The obtained value of the vehicle speed is equal to or lower than apredetermined second threshold speed

(2) An absolute value of the obtained acceleration is equal to or lowerthan a predetermined second threshold value

(3) The obtained value of the yaw-rate is equal to or lower than apredetermined second threshold rate.

Let us consider a first case where the obtained values of the vehiclebehavior parameters are beyond the respective second threshold ranges.In other words, let us consider a first case where the obtained value ofthe vehicle speed is higher than the second threshold speed, theabsolute value of the obtained acceleration is higher than the secondthreshold value, and the obtained value of the yaw-rate is higher thanthe second threshold rate.

In the first case, the image processing circuit 79 determines that theimage processing circuit 79 should output lane-marker detectioninformation to the lane departure detection ECU 778 b.

Otherwise, let us consider a second case where the obtained values ofthe vehicle behavior parameters are within the respective secondthreshold ranges. In other words, let us consider a second case wherethe obtained value of the vehicle speed is equal to or lower than thesecond threshold speed, the absolute value of the obtained accelerationis equal to or lower than the second threshold value, and the obtainedvalue of the yaw-rate is higher than the second threshold rate. In thesecond case, the image processing circuit 79 determines that the imageprocessing circuit 79 should not output lane-marker detectioninformation to the lane departure detection ECU 778 b.

When receiving the lane-marker detection information sent from the imageprocessing circuit 79 and the sensor signals sent from the respectivesensors 761 to 763, the lane departure detection ECU 778 b is configuredto determine whether

(1) A probability of the vehicle V unintentionally leaving, i.e.departing from, a lane on which the vehicle V is running is higher thana threshold probability or

(2) The vehicle V has unintentionally left a lane on which the vehicle Vwas running.

The lane departure detection ECU 778 b controls a corresponding actuatorof at least one of the warning devices 781 to 784 to activate it when itis determined that

(1) The probability of the vehicle V unintentionally leaving the lane onwhich the vehicle V is running is higher than the threshold probabilityor

(2) The vehicle V has unintentionally left the lane on which the vehicleV was running.

The at least one of the warning devices 781 to 784 is activated tooutput warning information for the occupants of the vehicle V.

The lane departure detection ECU 778 b can send a control signal to theactuator of the steering device 771 to adjust the steering angle of thesteering wheel when it is determined that

(1) The probability of the vehicle V unintentionally leaving the lane onwhich the vehicle V is running is higher than the threshold probabilityor

(2) The vehicle V has unintentionally left the lane on which the vehicleV was running.

The adjustment of the steering angle of the steering wheel prevents thevehicle V from unintentionally leaving the lane or returns the vehicleV, which unintentionally left the lane, to the lane.

As described above, the lane departure detection ECU 778 b uses thelane-marker detection information for controlling the actuators of atleast one of the warning devices 781 to 784 and the steering device 771.In other words, the lane-marker detection information serves as signalsto control the actuators of the one or more warning devices 781 to 784and the steering device 771 installed in the vehicle V.

As described above, the image processing circuit 79 successivelycaptures images successively sent from the image sensor 33 a, andobtains the sensor signals sent from the respective sensors 761 to 763via the bus 74. Then, the image processing circuit 79 performs varioustasks including the tasks 40 a to 40 c set forth above, based on thecaptured images and the sensor signals. Based on the results of thevarious tasks and the sensor signals, the image processing circuit 79outputs control signals to at least one of the actuators of targetdevices to be controlled by at least one of the vehicle control module77 and the HMI module 78.

Next, the structure of the camera module 3 according to the embodimentwill be described in detail with reference to FIGS. 9 and 10.

The camera module 3 includes the lens assembly 3A. The lens assembly 3Ais comprised of a lens barrel 31 including a plurality of lenses, and alens holder 32. The camera module 3 also includes a camera board 33.

The lens barrel 31 includes a tubular body 31 a made of, for example, aresin in which the plurality of lenses (for example, 311 to 314illustrated in FIG. 13) are disposed to be coaxially aligned with eachother.

The lens holder 32 is made of, for example, a resin, and holds the lensbarrel 31 to thereby hold the plurality of lenses 311 to 314. The lensbarrel 31 can be integrally formed with the lens holder 32, so that thelens holder 32 directly holds the plurality of lenses 311 to 314.

The lens holder 32 has a substantially plate-like base 32 a constitutinga second air-passage defining structure described later. The base 32 ais arranged such that its major surfaces are directed to the front andrear directions of the vehicle V. The lens holder 32 also has a tubularholding body 320 attached to one major surface, i.e. a front surface, ofthe base 32 a such that a center axis of the tubular holding body 320extends along the front-rear direction of the vehicle V. The tubularholding body 320 holds the lens barrel 31 such that the optical axes 310of the lenses 311 to 314 are aligned with the center axis thereof.

The camera board 33 is implemented with the image sensor 33 a forpicking up images of a region ahead of the vehicle V. The camera board33 is fixedly attached to the other major surface, i.e. the rearsurface, of the base 32 a such that the center of the image sensor 33 ais located through which the optical axis 310 of the lenses 311 to 314passes. The camera module 3 is installed in the housing 2 such that thecamera board 33 faces the opening 21 of the housing 2.

A two-dimensional CMOS image sensor comprised of CMOS semiconductorcells arranged in a two-dimensional array or a two-dimensional CCD imagesensor comprised of photodiodes arranged in a two-dimensional array canbe used as the image sensor 33 a.

Note that the electrical connection harness 5 is for example designed asa wiring board, such as a flexible printed wiring board, and wiresprinted on the wiring board connect the image sensor 33 a and otherelements implemented on the camera board 33 to the circuits includingthe image processing circuit 79 and implemented on the control circuitsubstrate 4.

Referring to FIG. 9, the tubular holder body 320 has an uppersemi-tubular wall 320 a mounted on the front surface of the base 32 aand having an opening 320 b in which one end, i.e. a rear-side end, ofthe lens barrel 31 is fitted. The tubular holder body 320 also has asurrounding wall 320 c having a substantially C shape with both upperends spaced apart. The surrounding wall 320 c extends integrally fromthe annular periphery of the upper semi-tubular wall 320 a in the frontdirection of the vehicle V, and surrounds the other end, i.e. afront-side end, of the lens barrel 31.

The lens holder 32 includes a first air-passage defining structure 321,a second air-passage defining structure 322, a third air-passagedefining structure 323, and a fourth air-passage defining structure 324;these structures, i.e. mechanisms, are integrally formed with thetubular holder body 320. Each of the first to fourth air-passagedefining structures 321 to 324 is configured to define a correspondingpassage for guiding air, which is entering, through the opening 21 ofthe housing 2 from the outside thereof, the inside the housing 2 whiledetouring the air into the inside of the housing 2. This results inreduction of the possibility that condensation occurs on each of thecontrol circuit board 4 and the camera board 33.

The first air-passage defining structure 321 is comprised of aplate-like flange wall 321 a extending, from the lower side of theperiphery of the surrounding wall 320 c, toward the lower side and thelateral side thereof and perpendicular to the front-rear direction ofthe vehicle V. The first air-passage defining mechanism 321 is alsocomprised of a plate-like bottom wall 321 b continuously extending froma lower end of the flange wall 321 a in the front direction of thevehicle V perpendicular to the flange wall 321 a, the flange wall 321 aextending in the vertical direction of the vehicle V.

The first air-passage defining structure 321 includes a plate-likeleft-hand wall 321 c continuously extending from a left-hand end of theflange wall 321 a and a left-hand end of the bottom wall 321 bperpendicular to the flange wall 321 a and the bottom wall 321 b.

The first air-passage defining structure 321 includes a plate-likeright-hand wall 321 d continuously extending from a right-hand end ofthe flange wall 321 a and a right-hand end of the bottom wall 321 bperpendicular to the flange wall 321 a and the bottom wall 321 b.

The second air-passage defining structure 322 is comprised of theplate-like base 32 a. The base 32 a is designed to have the majorsurfaces, i.e. front and rear surfaces, larger than the area of theannular end of the upper semi-tubular wall 320 a mounted on the frontsurface of the base 32 a. In other words, the upper semi-tubular wall320 a of the tubular holder body 320 is mounted on a substantiallycenter portion of the front surface of the base 32 a.

The third air-passage defining structure 323 is comprised of aplate-like projection 323 a projecting in the left direction from aradially leftmost edge of the upper semi-tubular wall 320 a and aradially leftmost edge of the surrounding wall 320 c.

The fourth air-passage defining structure 324 is comprised of aplate-like projection 324 a projecting in the right direction from aradially rightmost edge of the upper semi-tubular wall 320 a and aradially rightmost edge of the surrounding wall 320 c.

Next, the respective first to fourth air-passage defining structures 321to 324 when the camera module 3 is installed in the housing 2 will bedescribed in detail hereinafter with reference to FIGS. 11 to 14.

First, the first air-passage defining structure 321 for defining a firstair-passage located below the lens barrel 31 will be describedhereinafter.

The first air-passage defining structure 321 is comprised of the concaverecess 22 c in addition to the walls 321 a to 321 d. Referring to FIG.13, the concave recess 22 c has a rear-side surface located to face afront surface of the flange wall 321 a with a slight clearancetherebetween in the front-rear direction. The clearance constitutes alower upstream air-passage 11. In other words, the concave recess 22 cand the flange wall 321 a constitute the lower upstream air-passage 11.

In addition, the concave recess 22 c has a bottom surface located toface a top surface of the bottom wall 321 b with a slight clearancetherebetween in the vertical direction. The clearance constitutes alower midstream air-passage 12. In other words, the concave recess 22 cand the bottom wall 321 b constitute the lower midstream air-passage 12.The lower upstream air-passage 11 extends in the vertical direction, andthe lower midstream air-passage 12 communicates with the lower upstreamair-passage 11 and extends, perpendicular to the extending direction ofthe lower upstream air-passage 11, in the forward direction from thelower end of the lower upstream air-passage 11. In other words, theassembly of the air-passages 11 and 12 has a portion bent at a suitableangle, for example right angles, between the air-passages 11 and 12.

The lower upstream air passage 11 forcibly guides air, such as warm air,which is entering through the opening 21 toward the inside of thehousing 2, to be oriented downward (see arrow 51 in FIG. 13). The topsurface of the bottom wall 321 b changes the orientation 51 of the airflowing through the lower upstream air-passage 11 to the orientation(see arrow 52 in FIG. 13) bypassing the control circuit board 4 at thelowermost end of the lower upstream air-passage 11. This guides the airflowing through the lower upstream air-passage 11 into the lowermidstream air-passage 12. The lower midstream air-passage 12continuously guides the air to the orientation 52 to be detoured fromthe control circuit board 4.

The area formed by the periphery of the opening 21 of the housing 2serves as an entrance connecting between the outside and inside of thehousing 2. In other words, if the closed curve of the periphery of theopening 21 consists of a plurality of points, a line between each of thepoints with respect to a corresponding point of the lens holder 32,which has the shortest distance therebetween, is referred to as aminimum line. In this case, a plane constructed to contain all theminimum lines serves as the entrance connecting between the outside andinside of the housing 2. In other words, the entrance serves as aboundary plane between the outside and inside of the housing 2.

The first air-passage defining structure 321 has a partition wall 24projecting downward from the lower end of the front portion of theconcave recess 22 c.

The partition wall 24 has a rear surface located to face a front surfaceof the bottom wall 321 b with a slight clearance therebetween in thefront-rear direction. The clearance constitutes a lower downstreamair-passage 13. In other words, the bottom wall 321 b and thepartitioning wall 24 constitute the lower downstream air-passage 13. Thelower downstream air-passage 13 has an upper end communicating with thefront end of the lower midstream air-passage 12, and extends,perpendicular to the extending direction of the lower midstreamair-passage 12, downward toward one of components 41 implemented on thecontrol circuit board 4 (see arrow 53 in FIG. 13); the one of thecomponents 41 faces the lower downstream air-passage 13. In other words,the assembly of the air-passages 12 and 13 has a portion bent at asuitable angle, for example right angles, between the air-passages 12and 13.

Specifically, the lower upstream air-passage 11, the lower midstreamair-passage 12, and the lower downstream air-passage 13 constitute thefirst air-passage defined by the first air-passage defining structure321, to which a reference numeral (11, 12, 13) will be assigned. Thefirst air-passage (11, 12, 13) has two corners through each of which theorientation of air entering the first air-passage (11, 12, 13) ischanged. In other words, the first air-passage (11, 12, 13) has asubstantially crank shape including two portions each bent at, forexample, right angles. To put it another way, the first air-passage (11,12, 13) is stepped to have one step as an example of a labyrinthstructure. Each of the two portions of the first air-passage (11, 12,13) is not limited to be bent at right angles, and can be bent at otherdesired angles.

From another perspective, the first air-passage defining structure 321narrows a space around the lens barrel 31 in the housing 2 to the firstair-passage (11, 12, 13) comprised of the lower upstream air-passage 11,the lower midstream air-passage 12, and the lower downstream air-passage13. That is, air, which tries to enter the inside of the housing 2 viathe opening 21, flows from a wide space around the opening 21, i.e. theentrance of the housing 2, into the narrowed first air-passage (11, 12,13), and thereafter, flows into a wide space in the housing 2.

The first air-passage defining structure 321 causes air to

(1) Flow through the lower upstream passage 11 downward (see the arrow51) to hit the top surface of the bottom 321 b

(2) Change in orientation to flow through the lower midstream passage 12in the front direction (see the arrow 52) deviated from, i.e.

the control circuit board 4 to hit the rear surface of the partitionwall 24

(3) Change in orientation to flow through the lower downstream passage13 downward (see the arrow 53) so as to flow in the housing 2.

Thus, even if the air flowing out of the lower downstream passage 13finally hits the control circuit board 4, the air has flowed throughsuch a labyrinthine course of the first air-passage (11, 12, 13), sothat the air has travelled a long distance and has hit the top surfaceof the bottom 321 b and the rear surface of the partition wall 24 twotimes. This results in the air, which has travelled a long distance,being sufficiently cooled before reaching the control circuit board 4.

The flow of air, which enters the inside of the housing 2 via theopening 21, passes through the narrowed passages 11, 12, and 13, so thatthe velocity of the flow of air is reduced. This reduces the possibilitythat air containing a water content reaches the control circuit board 4,thus reducing the possibility of the occurrence of condensation on thecontrol circuit board 4.

Note that the size, i.e. the width, of the lower upstream passage 11 inthe front-rear direction, the size, i.e. the width, of the lowermidstream passage 12 in the vertical direction, and the size, i.e. thewidth, of the lower downstream passage 13 in the front-rear directioncan be adjusted. The narrower one or more the passages 11 to 13 are, themore the velocity of the flow of air is reduced. From another viewpoint,the first air-passage (11, 12, 13) also serves as a route through whichheat generated in the housing 2 is transferred to be exhausted from theopening 21 toward the outside of the housing 2.

For these reasons, the width, of the lower upstream passage 11 in thefront-rear direction, the width, of the lower midstream passage 12 inthe vertical direction, and the width, of the lower downstream passage13 in the front-rear direction are preferably adjusted to satisfy boththe capability of preventing condensation and the capability oftransferring heat from the inside of the housing 2.

Next, the second air-passage defining structure 322 for defining asecond air-passage located above the lens holder 32 will be describedhereinafter.

Referring to FIGS. 11 and 13, the second air-passage defining structure322 is comprised of a projection 25 c formed on a portion of the bottomsurface of the attachment wall 25 toward the upper semi-tubular wall 320a; the portion is located to face a top region 320 a 1 of the uppersemi-tubular wall 320 a. Specifically, the projection 25 c has a bottomsurface parallel to the top region 320 a 1 of the upper semi-tubularwall 320 a with a slight clearance therebetween in the verticaldirection. The clearance constitutes an upper upstream air-passage 14 a.In other words, the projection 25 c and the upper semi-tubular wall 320a constitute the upper upstream air-passage 14 a.

In addition, referring to FIG. 13, the projection 25 c has a rear-sidesurface located to face the front surface of the base 32 a with a slightclearance therebetween in the front-rear direction. The clearanceconstitutes an upper midstream air-passage 14 b. In other words, theprojection 25 c and the base 32 a constitute the upper midstreamair-passage 14 b. The upper upstream air-passage 14 a extends in thefront-rear direction, and the upper midstream air-passage 14 bcommunicates with the rear end of the upper upstream air-passage 14 aand extends, perpendicular to the extending direction of the upperupstream air-passage 14 a, in the vertical direction from the rear endof the upper upstream air-passage 14 a. In other words, the assembly ofthe air-passages 14 a and 14 b has a portion bent at a suitable angle,for example right angles, between the air-passages 14 a and 14 b.

Referring to FIG. 13, the bottom surface of the attachment wall 25 islocated to face an upper surface of the base 32 a with a slightclearance therebetween in the vertical direction. The clearanceconstitutes an upper downstream air-passage 14 c. In other words, theattachment wall 25 a and the base 32 a constitute the upper downstreamair-passage 14 c. The upper downstream air-passage 14 c has a front endcommunicating with the upper end of the upper midstream air-passage 14b, and extends, perpendicular to the extending direction of the uppermidstream air-passage 14 b, in the rear direction. In other words, theassembly of the air-passages 14 b and 14 c has a portion bent at asuitable angle, for example right angles, between the air-passages 14 band 14 c.

The upper upstream air passage 14 a forcibly guides air, such as warmair, which is entering through the opening 21 toward the inside of thehousing 2, to be oriented in the rear direction (see arrow 54 in FIG.13). The front surface of the base 32 a changes the orientation 54 ofthe air flowing through the upper upstream air-passage 14 a to theorientation (see arrow 55 in FIG. 13) bypassing the camera board 33 atthe rear end of the upper upstream air-passage 14 a. This guides the airflowing through the upper upstream air-passage 14 a into the uppermidstream air-passage 14 b. The upper midstream air-passage 14 bcontinuously guides the air to the orientation 55 to be detoured fromthe camera board 33.

The bottom surface of the attachment wall 25 changes the orientation 55of the air flowing through the upper midstream air-passage 14 b to theorientation 56 in the rear direction. The upper downstream air-passage14 c continuously guides the air with the changed orientation 56 to therear direction

Specifically, the upper upstream air-passage 14 a, the upper midstreamair-passage 14 b, and the upper downstream air-passage 14 c constitutethe second air-passage defined by the second air-passage definingstructure 322, to which a reference numeral (14 a, 14 b, 14 c) will beassigned. The second air-passage (14 a, 14 b, 14 c) has two cornersthrough each of which the orientation of air entering the secondair-passage (14 a, 14 b, 14 c) is changed. In other words, the secondair-passage (14 a, 14 b, 14 c) has a substantially crank shape includingtwo portions each bent at, for example, right angles. To put it anotherway, the second air-passage (14 a, 14 b, 14 c) is stepped to have onestep as an example of a labyrinth structure. Each of the two portions ofthe second air-passage (14 a, 14 b, 14 c) is not limited to be bent atright angles, and can be bent at other desired angles.

From another perspective, the second air-passage defining structure 322narrows a space between the lens holder 32 and the attachment wall 25 tothe second air-passage (14 a, 14 b, 14 c) comprised of the upperupstream air-passage 14 a, the upper midstream air-passage 14 b, and theupper downstream air-passage 14 c. That is, air, which tries to enterthe inside of the housing 2 via the opening 21, flows from a wide spacearound the opening 21, i.e. the entrance of the housing 2, into thenarrowed second air-passage (14 a, 14 b, 14 c), and thereafter, flowsinto a wide space in the housing 2.

The second air-passage defining structure 322 causes air to

(1) Flow through the upper upstream passage 14 a in the rear direction(see the arrow 54) to hit the front surface of the base 32 a

(2) Change in orientation to flow through the upper midstream passage 14b in the vertical direction (see the arrow 55) so as not to be directedtoward the camera board 33 to hit the bottom surface of the attachmentwall 25

(3) Change in orientation to flow through the upper downstream passage14 c in the rear direction (see the arrow 56) so as to flow in thehousing 2.

Thus, even if the air flowing out of the upper downstream passage 14 cfinally hits the camera board 33, the air has flowed through such alabyrinthine course of the second air-passage (14 a, 14 b, 14 c), sothat the air has travelled a long distance and has hit the front surfaceof the base 32 a and the bottom surface of the attachment wall 25 twotimes. This results in the air, which has travelled a long distance,being sufficiently cooled before reaching the camera board 33. Notethat, even if the air flowing out of the upper downstream air-passage 14c comes around behind the camera board 33, it is possible to reduce thepossibility of the occurrence of condensation on the rear surface of thecamera board 33.

The flow of air, which enters the inside of the housing 2 via theopening 21, passes through the narrowed passages 14 a, 14 b, and 14 c,so that the velocity of the flow of air is reduced. This reduces thepossibility that air containing a water content reaches the camera board33, thus reducing the possibility of the occurrence of condensation onthe camera board 33.

Note that the size, i.e. the width, of the upper upstream passage 14 ain the vertical direction, the size, i.e. the width, of the uppermidstream passage 14 b in the front-rear direction, and the size, i.e.the width, of the upper downstream passage 14 c in the verticaldirection can be adjusted. The narrower one or more the passages 14 a to14 c are, the more the velocity of the flow of air is reduced. Fromanother viewpoint, the second air-passage (14 a, 14 b, 14 c) also servesas a route through which heat generated in the housing 2 is transferredto be exhausted from the opening 21 toward the outside of the housing 2.

For these reasons, the width of the upper upstream passage 14 a in thevertical direction, the width of the upper midstream passage 14 b in thefront-rear direction, and the width of the upper downstream passage 14 cin the vertical direction are preferably adjusted to satisfy both thecapability of preventing condensation and the capability of transferringheat from the inside of the housing 2.

Next, the left air-passage defining structure 323 for defining a thirdair-passage located at the left side of the lens holder 32 will bedescribed hereinafter.

Referring to FIG. 14, the C-shaped surrounding wall 320 c has aleft-hand curved portion 320 c 1. The left-hand curved portion 320 c 1is convexly curved from the left-hand upper end toward the radiallyleftmost edge of the C-shaped surrounding wall 320 c, and faces theleft-hand end 26 of the attachment wall 25.

The left-hand end 26 of the attachment wall 25 has an inner surface 26 athat faces the surrounding wall 320 c. The left-hand end 26 has aprojection 26 b projecting toward the left-hand curved portion 320 c 1of the surrounding wall 320 c. The projection 26 b of the left-hand end26 has a concavely curved inner surface 26 c that faces the outersurface of the left-hand curved portion 320 c 1 with a slight clearancetherebetween. The clearance constitutes a left upstream air-passage 16a. In other words, the left air-passage defining structure 323 includesthe left-hand end 26 of the attachment wall 25, and the surrounding wall320 c of the tubular holder body 320.

In addition, referring to FIG. 14, the C-shaped surrounding wall 320 chas the projection 323 a that projects in the left direction from theradially leftmost edge of the C-shaped surrounding wall 320 c.

The projection 26 b of the left-hand end 26 has a bottom surface thatfaces an upper surface of the projection 323 a with a slight clearancetherebetween. The clearance constitutes a left midstream air-passage 16b. In other words, the left air-passage defining structure 323 includesthe left-hand end 26 of the attachment wall 25, and the surrounding wall320 c of the tubular holder body 320.

The left upstream air-passage 16 a extends downward along the outersurface of the left-hand curved portion 320 c 1, and the left midstreamair-passage 16 b communicates with the lower end of the left upstreamair-passage 16 a, and extends, across the extending direction of theleft upstream air-passage 16 a, in the left-hand direction from thelower end of the left upstream air-passage 16 a.

Referring to FIG. 14, the inner surface 26 a of the left-hand end 26 ofthe attachment wall 25 faces the left-hand surface of the projection 323a with a slight clearance therebetween in the vehicle width direction.The clearance constitutes a left downstream air-passage 16 c. In otherwords, the left air-passage defining structure 323 includes theleft-hand end 26 of the attachment wall 25, and the surrounding wall 320c of the tubular holder body 320.

The left downstream air-passage 16 c communicates with the left-hand endof the left midstream air-passage 16 b, and extends, perpendicular tothe extending direction of the left midstream air-passage 16 b, downwardfrom the left-hand end of the left midstream air-passage 16 b. In otherwords, the assembly of the air-passages 14 b and 14 c has a portion bentat a suitable angle, for example right angles, between the air-passages14 b and 14 c.

The left-hand upstream air passage 16 a forcibly guides air, such aswarm air, which is entering through the opening 21 toward the inside ofthe housing 2, to be oriented downward along the outer surface of theleft-hand curved portion 320 c 1 (see arrow 61 in FIG. 14). The uppersurface of the projection 323 a changes the orientation 61 of the airflowing through the left upstream air-passage 16 a to the orientation(see arrow 62 in FIG. 14) bypassing the control circuit board 4 at thelower end of the left upstream air-passage 16 a. This guides the airflowing through the left upstream air-passage 16 a into the leftmidstream air-passage 16 b. The left midstream air-passage 16 bcontinuously guides the air to the orientation 62 so as not to bedirected toward the control circuit board 4.

The inner surface 26 a of the left-hand end 26 of the attachment wall 25changes the orientation 62 of the air flowing through the left midstreamair-passage 16 b downward in the orientation 63. The left downstreamair-passage 16 c continuously guides the air downward.

Specifically, the left upstream air-passage 16 a, the left midstreamair-passage 16 b, and the left downstream air-passage 16 c constitutethe third air-passage defined by the third air-passage definingstructure 323, to which a reference numeral (16 a, 16 b, 16 c) will beassigned. The third air-passage (16 a, 16 b, 16 c) has two cornersthrough each of which the orientation of air entering the thirdair-passage (16 a, 16 b, 16 c) is changed.

In other words, the third air-passage (16 a, 16 b, 16 c) has asubstantially crank shape including two portions each bent at, forexample, right angles. To put it another way, the third air-passage (16a, 16 b, 16 c) is stepped to have one step as an example of a labyrinthstructure. Each of the two portions of the third air-passage (16 a, 16b, 16 c) is not limited to be bent at right angles, and can be bent atother desired angles.

From another perspective, the third air-passage defining structure 323narrows a space between the lens holder 32 and the left-hand end 26 ofthe attachment wall 25 to the third air-passage (16 a, 16 b, 16 c)comprised of the left upstream air-passage 16 a, the left midstreamair-passage 16 b, and the left downstream air-passage 16 c. That is,air, which tries to enter the inside of the housing 2 via the opening21, flows from a wide space around the opening 21, i.e. the entrance ofthe housing 2, into the narrowed third air-passage (16 a, 16 b, 16 c),and thereafter, flows into a wide space in the housing 2.

The third air-passage defining structure 323 causes air to

(1) Flow through the left upstream passage 16 a downward along the outersurface of the left-hand curved portion 320 c 1 (see arrow 61) to hitthe upper surface of the projection 323 a

(2) Change in orientation to flow through the left midstream passage 16b in the left direction (see the arrow 62) so as not to be directedtoward the control circuit board 4 to hit the inner surface 26 a of theleft-hand end 26 of the attachment wall 25

(3) Change in orientation to flow through the left downstream passage 16c downward (see the arrow 63) so as to flow in the housing 2.

Thus, even if the air flowing out of the left downstream passage 16 cfinally hits the control circuit board 4, the air has flowed throughsuch a labyrinthine course of the third air-passage (16 a, 16 b, 16 c),so that the air has travelled a long distance and has hit the uppersurface of the projection 323 a and the inner surface 26 a of theleft-hand end 26 of the attachment wall 25 two times. This results inthe air, which has travelled a long distance, being sufficiently cooledbefore reaching the control circuit board 4.

The flow of air, which enters the inside of the housing 2 via theopening 21, passes through the narrowed passages 16 a, 16 b, and 16 c,so that the velocity of the flow of air is reduced. This reduces thepossibility that air containing a water content reaches the controlcircuit board 4, thus reducing the possibility of the occurrence ofcondensation on the control circuit board 4.

Note that the size, i.e. the width, of the left upstream passage 16 a inthe vehicle width direction, the size, i.e. the width, of the leftmidstream passage 16 b in the vertical direction, and the size, i.e. thewidth, of the left downstream passage 16 c in the vehicle widthdirection can be adjusted. The narrower one or more the passages 16 a to16 c are, the more the velocity of the flow of air is reduced. Fromanother viewpoint, the third air-passage (16 a, 16 b, 16 c) also servesas a route through which heat generated in the housing 2 is transferredto be exhausted from the opening 21 toward the outside of the housing 2.

For these reasons, the width of the left upstream passage 16 a in thevehicle width direction, the width of the left midstream passage 16 b inthe vertical direction, and the width of the left downstream passage 16c in the vehicle width direction are preferably adjusted to satisfy boththe capability of preventing condensation and the capability oftransferring heat from the inside of the housing 2.

Next, the right air-passage defining structure 324 for defining a fourthair-passage located at the right side of the lens holder 32 will bedescribed hereinafter.

Referring to FIG. 14, the C-shaped surrounding wall 320 c has aright-hand curved portion 320 c 2. The right-hand curved portion 320 c 2is convexly curved from the right-hand upper end toward the radiallyrightmost edge of the C-shaped surrounding wall 320 c, and faces theright-hand end 27 of the attachment wall 25.

The right-hand end 27 of the attachment wall 25 has an inner surface 27a that faces the surrounding wall 320 c. The right-hand end 27 has aprojection 27 b projecting toward the right-hand curved portion 320 c 2of the surrounding wall 320 c. The projection 27 b of the right-hand end27 has a concavely curved inner surface 27 c that faces the outersurface of the right-hand curved portion 320 c 2 with a slight clearancetherebetween. The clearance constitutes a right upstream air-passage 18a. In other words, the right air-passage defining structure 324 includesthe right-hand end 27 of the attachment wall 25, and the surroundingwall 320 c of the tubular holder body 320.

In addition, referring to FIG. 14, the C-shaped surrounding wall 320 chas the projection 324 a that projects in the right direction from theradially rightmost edge of the C-shaped surrounding wall 320 c.

The projection 27 b of the right-hand end 27 has a bottom surface thatfaces an upper surface of the projection 324 a with a slight clearancetherebetween. The clearance constitutes a right midstream air-passage 18b. In other words, the right air-passage defining structure 324 includesthe right-hand end 26 of the attachment wall 25, and the surroundingwall 320 c of the tubular holder body 320.

The right upstream air-passage 18 a extends downward along the outersurface of the right-hand curved portion 320 c 2, and the rightmidstream air-passage 18 b communicates with the lower end of the rightupstream air-passage 18 a, and extends, across the extending directionof the right upstream air-passage 18 a, in the right-hand direction fromthe lower end of the right upstream air-passage 18 a.

Referring to FIG. 14, the inner surface 27 a of the right-hand end 27 ofthe attachment wall 25 faces the right-hand surface of the projection324 a with a slight clearance therebetween in the vehicle widthdirection. The clearance constitutes a right downstream air-passage 18c. In other words, the right air-passage defining structure 324 includesthe right-hand end 27 of the attachment wall 25, and the surroundingwall 320 c of the tubular holder body 320.

The right downstream air-passage 18 c communicates with the right-handend of the right midstream air-passage 18 b, and extends, perpendicularto the extending direction of the right midstream air-passage 18 b,downward from the right-hand end of the right midstream air-passage 18b. In other words, the assembly of the air-passages 18 b and 18 c has aportion bent at a suitable angle, for example right angles, between theair-passages 18 b and 18 c.

The right-hand upstream air passage 18 a forcibly guides air, such aswarm air, which is entering through the opening 21 toward the inside ofthe housing 2, to be oriented downward along the outer surface of theright-hand curved portion 320 c 2 (see arrow 64 in FIG. 14). The uppersurface of the projection 324 a changes the orientation 64 of the airflowing through the right upstream air-passage 18 a to the orientation(see arrow 65 in FIG. 14) bypassing the control circuit board 4 at thelower end of the right upstream air-passage 18 a. This guides the airflowing through the right upstream air-passage 18 a into the rightmidstream air-passage 18 b. The right midstream air-passage 18 bcontinuously guides the air to the orientation 65 so as not to bedirected toward the control circuit board 4.

The inner surface 27 a of the right-hand end 27 of the attachment wall25 changes the orientation 65 of the air flowing through the rightmidstream air-passage 18 b downward in the orientation 66. The rightdownstream air-passage 18 c continuously guides the air downward.

Specifically, the right upstream air-passage 18 a, the right midstreamair-passage 18 b, and the right downstream air-passage 18 c constitutethe fourth air-passage defined by the fourth air-passage definingstructure 324, to which a reference numeral (18 a, 18 b, 18 c) will beassigned. The fourth air-passage (18 a, 18 b, 18 c) has two cornersthrough each of which the orientation of air entering the fourthair-passage (18 a, 18 b, 18 c) is changed.

In other words, the fourth air-passage (18 a, 18 b, 18 c) has asubstantially crank shape including two portions each bent at, forexample, right angles. To put it another way, the fourth air-passage (18a, 18 b, 18 c) is stepped to have one step as an example of a labyrinthstructure. Each of the two portions of the fourth air-passage (18 a, 18b, 18 c) is not limited to be bent at right angles, and can be bent atother desired angles.

From another perspective, the fourth air-passage defining structure 324narrows a space between the lens holder 32 and the right-hand end 27 ofthe attachment wall 25 to the fourth air-passage (18 a, 18 b, 18 c)comprised of the right upstream air-passage 18 a, the right midstreamair-passage 18 b, and the right downstream air-passage 18 c. That is,air, which tries to enter the inside of the housing 2 via the opening21, flows from a wide space around the opening 21, i.e. the entrance ofthe housing 2, into the narrowed fourth air-passage (18 a, 18 b, 18 c),and thereafter, flows into a wide space in the housing 2.

The fourth air-passage defining structure 324 causes air to

(1) Flow through the right upstream passage 18 a downward along theouter surface of the right-hand curved portion 320 c 2 (see arrow 64) tohit the upper surface of the projection 324 a

(2) Change in orientation to flow through the right midstream passage 18b in the right direction (see the arrow 65) so as not to be directedtoward the control circuit board 4 to hit the inner surface 27 a of theright-hand end 27 of the attachment wall 25

(3) Change in orientation to flow through the right downstream passage18 c downward (see the arrow 66) so as to flow in the housing 2.

Thus, even if the air flowing out of the right downstream passage 18 cfinally hits the control circuit board 4, the air has flowed throughsuch a labyrinthine course of the fourth air-passage (18 a, 18 b, 18 c),so that the air has travelled a long distance and has hit the uppersurface of the projection 324 a and the inner surface 27 a of theright-hand end 27 of the attachment wall 25 two times. This results inthe air, which has travelled a long distance, being sufficiently cooledbefore reaching the control circuit board 4.

The flow of air, which enters the inside of the housing 2 via theopening 21, passes through the narrowed passages 18 a, 18 b, and 18 c,so that the velocity of the flow of air is reduced. This reduces thepossibility that air containing with a water content reaches the controlcircuit board 4, thus reducing the possibility of the occurrence ofcondensation on the control circuit board 4.

Note that the size, i.e. the width, of the right upstream passage 18 ain the vehicle width direction, the size, i.e. the width, of the rightmidstream passage 18 b in the vertical direction, and the size, i.e. thewidth, of the right downstream passage 18 c in the vehicle widthdirection can be adjusted. The narrower one or more the passages 18 a to18 c are, the more the velocity of the flow of air is reduced. Fromanother viewpoint, the fourth air-passage (18 a, 18 b, 18 c) also servesas a route through which heat generated in the housing 2 is transferredto be exhausted from the opening 21 toward the outside of the housing 2.

For these reasons, the width of the right upstream passage 18 a in thevehicle width direction, the width of the right midstream passage 18 bin the vertical direction, and the width of the right downstream passage18 c in the vehicle width direction are preferably adjusted to satisfyboth the capability of preventing condensation and the capability oftransferring heat from the inside of the housing 2.

As described above, the first, second, third, and fourth air-passages(11, 12, 13), (14 a, 14 b, 14 c), (16 a, 16 b, 16 c), and (18 a, 18 b,18 c) result in reduction of the possibility of condensation occurringon each of the circuit boards (control circuit board 4 and camera board33) without sealing the housing 2 and using drip-proof materials.Particularly, the imaging device 1 achieves the aforementioned advantagebased on simple structural ideas applied to the assembly of the housing2 and the camera holder 32.

The advantage of reducing the possibility of condensation occurring oneach of the circuit boards 4 and 33 sufficiently reduces the possibilityof water migration being produced in each of the circuit boards 4 and34, thus sufficiently reducing the possibility of the occurrence ofinsulation failures in each of the circuit boards 3 and 33.

The first, second, third, and fourth air-passages (11, 12, 13), (14 a,14 b, 14 c), (16 a, 16 b, 16 c), and (18 a, 18 b, 18 c) make difficultthat foreign materials, such as dusts, enter the inside of the housing 2through a space between the housing 2 and the lens holder 32. Thisimproves the quality reliability of each of the circuit boards 3 and 33.

The first, second, third, and fourth air-passages (11, 12, 13), (14 a,14 b, 14 c), (16 a, 16 b, 16 c), and (18 a, 18 b, 18 c) reduces

(1) The possibility of light entering the inside of the housing 2 viathe space between the housing 2 and the lens holder 32 and beingreflected by elements and/or portions in and/or on the housing 2 toproduce disturbance light

(2) The possibility of the disturbance light being detected by the imagesensor 33 a.

This results in the imaging device 1 having an improved performance ofrecognizing images.

The first, second, third, and fourth air-passage defining structures 321to 324 make hard that reflected images of elements installed in thehousing 2 are seen from the outside of the housing 2. This results inthe imaging device 1 having a better appearance when the imaging device1 is viewed through the front windshield 102 of the vehicle V.

The opening 21 is comprised of the U-shaped concave recess 21 a and theconcave recess 22 c, and the camera module 3 is arranged below theU-shaped concave recess 21 a. This arrangement results in the attachmentwall 25 being not located between the front windshield 102 and a part ofthe camera module 3 while the imaging device 1 is attached to the innersurface of the front windshield 102 (see FIG. 4). The part of the cameramodule 3 is, the front end of the lens barrel 31. This makes it possibleto locate the camera module 3 to be so close to the inner surface of thefront windshield 102 as to have the minimum distance between the innersurface of the front windshield 102 and the camera module 3 beingsmaller than the thickness of the attachment wall 25. This locationresults in the optical axes 310 of the lenses 311 to 314, which means acenter axis of an entrance pupil of the camera module 3, being closer tothe front windshield 102.

The U-shaped concave recess 21 a, which allows the center axis of theentrance pupil of the camera module 3 to be as close to the frontwindshield 102 as possible, makes it possible to reduce the size of thehood 9 for enhancement of the appearance of the imaging device 1.

Making the space between both left-hand and right-hand upper ends of theC-shaped surrounding wall 320 c of the tubular holder body 320 wider canresult in the camera module 3, i.e. the center axis of the entrancepupil of the camera module 3, being closer to the inner surface of thefront windshield 102.

The imaging device 1 is configured such that the U-shaped concave recess21 a of the attachment wall 25 is located to face the control circuitboard 4 and the camera board 33. This configuration may cause warm air,such as air transferred from a heating apparatus installed in thevehicle V to easily enter the inside of the housing 2 via the opening21. However, the first, second, third, and fourth air-passages (11, 12,13), (14 a, 14 b, 14 c), (16 a, 16 b, 16 c), and (18 a, 18 b, 18 c)efficiently reduce the possibility of condensation occurring on each ofthe control circuit board 4 and the camera board 33 due to the warm air.

Note that, as described above, the front, rear, right, and leftdirections described in the specification show the front, rear, right,and left directions of the vehicle V when the vehicle V is travelling inthe front direction of the vehicle V (see FIGS. 2, 13, and 14).Specifically, the optical axes 310 of the lenses 311 to 314 of the lensassembly 3A are in agreement with the front-rear direction of thevehicle V. The orientation of the optical axes 310 of the lenses 311 to314 toward an object to be captured by the lenses 310 to 314 is inagreement with the front direction of the vehicle V. The left-rightdirection is a direction perpendicular to both the optical axes 310 ofthe lenses 311 to 314 and the front-rear direction of the vehicle V. Inother words, the left is a left side when an object located in front ofthe vehicle V is seen by the lenses 311 to 314, and the right is a rightside when an object located in front of the vehicle V is seen by thelenses 311 to 314.

The present disclosure is not limited to the aforementioned embodiment.Elements of the imaging device 1 are not essential to imaging deviceswithin the scope of the present disclosure except where the elements areclearly described as essential elements or the elements are obviously tobe essential. Even if the number of elements, the values of elements,the amounts of elements, and the ranges of elements are disclosed in thespecification, the present disclosure is not limited thereto except thatthey are clearly described as essential or they are principallyestimated to be essential. Even if the shapes, locations, and positionalrelationships of elements are disclosed in the specification, thepresent disclosure is not limited thereto except that they are clearlydescribed as essential or they are principally estimated to beessential.

Specifically, the following modifications can be included within thescope of the present disclosure, and the modifications can beselectively applied to the embodiment in combination or alone. That is,at least some of the modifications can be freely applied to theembodiment.

Each of the first, second, third, and fourth air-passages (11, 12, 13),(14 a, 14 b, 14 c), (16 a, 16 b, 16 c), and (18 a, 18 b, 18 c) isconfigured to

(1) Guide air so as not to be directed toward a corresponding one of thecircuit boards 4 and 33

(2) Thereafter, guide the air to the orientation of a corresponding oneof the circuit boards 4 and 33.

The present disclosure is not limited to the configuration.

Specifically, each of the first, second, third, and fourth air-passages(11, 12, 13), (14 a, 14 b, 14 c), (16 a, 16 b, 16 c), and (18 a, 18 b,18 c) according to the first modification can be configured not tofinally guide the air to the orientation of a corresponding one of thecircuit boards 4 and 33.

An imaging device according to an example of the first modification isconfigured such that the partitioning wall 24 is eliminated from theconfiguration of the imaging device 1 (see FIG. 15). This configurationresults in elimination of the lower downstream air-passage 13, so thatair flowing through the lower midstream air-passage 12 continuouslyflows along an inner surface 22 e of the trapezoidal recess 22 opposingthe trapezoidal bottom surface 22 d in a direction independently in thedirection to the control circuit board 4 (see arrow 70 in FIG. 15). Thisconfiguration of the imaging device according to the first modificationfurther reduces the possibility of the occurrence of condensation oneach of the circuit boards 4 and 33.

Each of the top surface of the bottom wall 321 b, the front surface ofthe base 32 a, the upper surface of the projection 323 a, and the uppersurface of the projection 324 a changes the orientation of air flowingtoward a corresponding one of the circuit boards 4 and 33 to anotherorientation independent from the orientation toward a corresponding oneof the circuit boards 4 and 33. In the embodiment, each of the topsurface of the bottom wall 321 b, the front surface of the base 32 a,the upper surface of the projection 323 a, and the upper surface of theprojection 324 a is formed at the lens holder 32. The present disclosureis however not limited to this configuration.

Specifically, each of the top surface of the bottom wall 321 b, thefront surface of the base 32 a, the upper surface of the projection 323a, and the upper surface of the projection 324 a can be formed at thehousing 2. That is, each of the top surface of the bottom wall 321 b,the front surface of the base 32 a, the upper surface of the projection323 a, and the upper surface of the projection 324 a according to thesecond modification can be formed at the assembly of the housing 2 andthe camera holder 32.

Each of the first, second, third, and fourth air-passages (11, 12, 13),(14 a, 14 b, 14 c), (16 a, 16 b, 16 c), and (18 a, 18 b, 18 c) isdesigned as a hollow channel, but the present disclosure is not limitedthereto. Specifically, at least one of the first, second, third, andfourth air-passages (11, 12, 13), (14 a, 14 b, 14 c), (16 a, 16 b, 16c), and (18 a, 18 b, 18 c) according to the third modification can beconfigured such that a member, which lets air through, such as amoisture-permeable waterproof member, is contained therein.

As described above, no drop-proof materials are coated on the controlcircuit board 4 and the camera board 33, but an imaging device accordingto the fourth modification can be configured such that one or moredrop-proof materials can be coated on the control circuit board 4 and/orthe camera board 33. This may result in further reduction of thepossibility of condensation occurring on the control circuit board 4and/or the camera board 33.

The imaging device 1 according to the embodiment is used to be installedin vehicles, but the imaging device 1 according to the fifthmodification can be used for another apparatus.

The vehicle control module 77 according to the embodiment, whichincludes, for example, the headlight control ECU 778 a and the lanedeparture detection ECU 778 b, is located at the outside of the camerasystem 100 and installed in the vehicle V, but the present disclosure isnot limited thereto. Specifically, the vehicle control module 77according to the sixth modification can be implemented in the controlcircuit board 4. In the sixth modification, the vehicle control module77 including, for example, the headlight control ECU 778 a and the lanedeparture detection ECU 778 b, can be configured to send, to at leastone of the actuators of target devices installed in the vehicle V, acontrol signal for controlling the corresponding actuator based on boththe camera information sent from the image processing circuit 79 and thesensor signals sent from the respective sensors 761 to 763.

The vehicle control module 77 and the image processing circuit 79according to the embodiment is configured to send, to at least one ofthe actuators, a control signal for controlling the correspondingactuator based on both the camera information sent from the imageprocessing circuit 79 and the sensor signals sent from the respectivesensors 761 to 763. The present disclosure is however not limited to theconfiguration.

Specifically, the vehicle control module 77 according to the seventhmodification can be configured to send, to at least one of theactuators, a control signal for controlling the corresponding actuatorbased on either the camera information sent from the image processingcircuit 79 or the sensor signals sent from the respective sensors 761 to763.

The image processing circuit 79 is configured to perform, based on atleast one of the camera information sent from the image processingcircuit 79 and the sensor signals sent from the respective sensors 761to 763,

(1) The detection task 40 a to determine whether there is at least onelight source of a vehicle appearing in each of the captured images

(2) The light-source recognition task 40 b to determine whether the atleast one light source determined by the detection task 40 a is a lightsource, i.e. a tail lamp, of a preceding vehicle or a light source, i.e.a head lamp, of an oncoming vehicle

(3) The lane-marker detection task 40 c to detect the positions of lanemarkers painted on the road on which the vehicle V is running.

The present disclosure is however not limited to the configuration.

Specifically, the vehicle control module 77 according to the eighthmodification can be configured to perform, based on at least one of thecamera information sent from the image processing circuit 79 and thesensor signals sent from the respective sensors 761 to 763, arecognition task to detect at least one of

(1) The lanes ahead of the vehicle V including a lane on which thevehicle V is currently travelling, which will be referred to as laneinformation

(2) The shape of a road ahead of the travelling vehicle V, which will bereferred to as road-shape information

(3) The conditions of a road surface ahead of the travelling vehicle V,which will be referred to as road-surface information

(4) One or more light sources ahead of the vehicle V, which will bereferred to as light-source information

(5) One or more preceding vehicles including vehicles travellingadjacent to the vehicle V, which will be referred to aspreceding-vehicle information

(6) One or more oncoming vehicles, which will be referred to asoncoming-vehicle information

(7) One or more stopped vehicles around the vehicle V, which will bereferred to as stopped-vehicle information

(8) One or more preceding pedestrians around the vehicle V, which willbe referred to as preceding-pedestrian information

(9) One or more oncoming pedestrians around the vehicle V, which will bereferred to as oncoming-pedestrian information

(10) One or more stopping persons around the vehicle V, which will bereferred to as stopped-person information

(11) One or more motor cycles around the vehicle V, which will bereferred to as motor-cycle information

(12) One or more bicycles around the vehicle V, which will be referredto as bicycle information

(13) One or more obstacles around the vehicle V, which will be referredto as obstacle information

(14) One or more roadside objects around the vehicle V, which will bereferred to as roadside-object information

(15) One or more traffic signs around the vehicle V, which will bereferred to as traffic-sign information

(16) One or more traffic signals around the vehicle V, which will bereferred to as traffic-signal information

(17) One or more traffic markings around the vehicle V, which will bereferred to as traffic-marking information

(18) One or more advertising signs around the vehicle V, which will bereferred to as advertising-sign information

(19) A tunnel through which the vehicle V is going to go, which will bereferred to as tunnel information

(20) One or more emergency parking bays, which will be referred to asemergency-bay information

(21) Something that blocks the view of the camera module 3, which willbe referred to as camera-view blocking information

(22) Meteorological environments around the vehicle V, which will bereferred to as meteorological-environment information

(23) Building structures around the vehicle V, which will be referred toas building structure information.

The lanes ahead of the vehicle V including a lane on which the vehicle Vis currently travelling can be recognized based on the lane markersdetected by the lane-marker detection task 40 c.

The shape of a road represents the curvature or slope of the road, andthe conditions of a road include the degree of reflection on the roadsurface particularly if it is raining or snowing.

The light sources include a tail lamp of a preceding vehicle and a headlamp of an oncoming vehicle, and can be recognized by the light-sourcerecognition task 40 b set forth above.

The preceding pedestrians are pedestrians walking, ahead of the vehicleV, in a direction identical to the travelling direction of the vehicleV, and the oncoming pedestrians are pedestrians walking, ahead of thevehicle V, in a direction opposite to the travelling direction of thevehicle V. The stopping persons are persons stopping around the vehicleV, and the obstacles include, for example, rocks and the like. Theroadside objects include, for example, roadside curbs, roadsideguardrails, roadside poles, roadside trees, roadside fences, roadsidewalls, roadside buildings, roadside parked vehicles, roadside parkedbicycles, roadside electric poles, and so on. An emergency parking bayis a place provided at a shoulder of a road for getting out of the flowof traffic through the road. Something that obstructs the view of thecamera module 3 includes smudges attached to a portion of the frontwindshield 102, which is located in front of the lenses 311 to 314, orto at least one of the lenses 311 to 314. Something that obstructs theview of the camera module 3 also includes sheets or the like adhered ona portion of the front windshield 102, which is located in front of thelenses 311 to 314. The meteorological environments around the vehicle Vrepresent whether information around the vehicle V, such as rain, snow,fog, the degree of backlight, and the like.

The vehicle control module 77 receives the results of one or more imagerecognition tasks performed by the image processing circuit 79. Thevehicle control module 77 is configured to perform, based on the resultsof the one or more image recognition tasks, at least one of vehiclecontrol tasks including

(1) A lane departure warning task described hereinbefore

(2) A lane keeping task

(3) A headlight control task described hereinbefore

(4) A task for preventing broadside collisions

(5) A task for preventing collisions at intersections

(6) A task for preventing front collisions

(7) A sign displaying task

(8) A speed-limit displaying task

(9) An overspeed warning task

(10) An automatic wiper task

(11) A task for assisting lane changes

(12) An around view displaying task

(13) Automatic parking task

(14) An adaptive cruise control task

(15) A blind-spot warning task

(16) A rear cross-traffic warning task

(17) A front cross-traffic warning task

(18) An inter-vehicle distance warning task

(19) A rear-end collision warning task

(20) An erroneous start preventing task.

The lane keeping task is designed to send, based on the lane informationand the road-shape information, a control signal to the actuator of thesteering device 771 to adjust the steering angle of the steering, thuskeeping the vehicle V within the lane on which the vehicle V istravelling.

The headlight control task, i.e. high- and low-beam switching task andswiveling task, is performed by the headlight control ECU 778 a setforth above based on the lane information, the road-shape information,the road-surface information, and the light-source information.

The task for preventing broadside collisions is designed to

(1) Determine whether a probability that the vehicle V will collide withat least one moving object, such as a vehicle, a motor cycle, a bicycle,or the like, which is crossing at an intersection in front of thevehicle V, is higher than a predetermined threshold value

(2) Send a control signal to a target actuator, such as the actuator ofat least one of the steering device 771 and the brake 772, to controlthe target actuator when it is determined that the probability is higherthan the threshold value, thus avoiding the collision.

The task for preventing collisions at intersections is designed to

(1) Determine, when the vehicle V is turning at an intersection, whethera probability that the vehicle V will collide with at least one object,such as a vehicle, a motor cycle, a bicycle, a pedestrian, or the like,located around the vehicle V, is higher than a predetermined thresholdvalue

(2) Send a control signal to a target actuator, such as the actuator ofat least one of the steering device 771 and the brake 772, to controlthe target actuator when it is determined that the probability is higherthan the threshold value, thus avoiding the collision.

The task for preventing front collisions is designed to

(1) Determine whether a probability that the vehicle V will collide withat least one object, such as a preceding vehicle, a motor cycle, abicycle, a pedestrian, or the like, located ahead of the vehicle V ishigher than a predetermined threshold value

(2) Send a control signal to a target actuator, such as the actuator ofat least one of the steering device 771 and the brake 772, to controlthe target actuator when it is determined that the probability is higherthan the threshold value, thus avoiding the collision.

Note that each of the task for preventing broadside collisions, the taskfor preventing collisions at intersections, and the task for preventingfront collisions includes a task for

1. Determining whether the vehicle V can pass through a tunnel or belowan adverting sign when the tunnel or the advertising sign is detectedahead of the vehicle V

2. Send a control signal to a target actuator, such as the actuator ofat least one of the buzzer 781 and the speaker 782, to control thetarget actuator when it is determined that the vehicle V cannot passthrough the detected tunnel or below the detected adverting sign, thusavoiding a collision with the detected tunnel or the detectedadvertising sign.

Each of the task for preventing broadside collisions and the task forpreventing collisions at intersections is performed based on, forexample, the results of the one or more image recognition tasksassociated with

1. The road-surface information

2. The preceding-vehicle and oncoming-vehicle information

3. The stopped-vehicle information

4. The preceding-pedestrian and oncoming-pedestrian information

5. The stopped-person information

6. The motor-cycle and bicycle information

7. The obstacle and roadside-object information

8 The advertising-sign information

9. The tunnel information.

The sign displaying task is designed to send, based on at least one ofthe traffic-sign information, the traffic-signal information, thetraffic-marking information, the advertising-sign information, and soon, a control signal to the actuator of the display 784 so that thedisplay 784 displays at least one of the traffic-sign information, thetraffic-signal information, the traffic-marking information, theadvertising-sign information, and so on.

The speed-limit displaying task is designed to send, based on thetraffic-sign information, a control signal to the actuator of thedisplay 784 so that the display 784 displays a speed limit if the speedlimit is indicated by the traffic-sign information.

The overspeed warning task is designed to

1. Determine whether the speed of the vehicle V is exceeding the speedlimit indicated by the traffic-sign information

2. Send a control signal to the actuator of at least one of the buzzer781 and the speaker 782 when it is determined that the speed of thevehicle V is exceeding the speed limit indicated by the traffic-signinformation.

The control signal controls the actuator of at least one of the buzzer781 and the speaker 782, so that at least one of the buzzer 781 and thespeaker 782 audibly outputs a warning to occupants of the vehicle V; thewarning represents the overspeed of the vehicle V.

The automatic wiper task is designed to

(1) Determine whether the driver's visibility is lower than apredetermined threshold value based on the road-surface information andthe meteorological-environment information

(2) Send a control signal to the actuator of at least one of thewindshield wipers 777 so that at least one of the windshield wipers 777is activated to clean a corresponding at least one of the frontwindshield 102 and rear windshield from rain, snow, or other moisture.

The task for assisting lane changes is designed to, for example, detectanother vehicle travelling in a target lane adjacent to the lane onwhich the vehicle V is travelling based on the preceding-vehicleinformation. Then, the task for assisting lane changes is designed tosend control signals to the actuators of the respective steering device771, brake 772, automatic transmission 774, and directional indicator776 to control the devices 771, 772, 774, and 776 for assisting thedriver's operation for a lane change to the target lane according to thedetected adjacent vehicle.

The around view displaying task is designed to send, to the actuator ofthe display 784, a control signal so that the display 784 displays anaround-view image covering the surroundings of the vehicle V. Theautomatic parking task is designed to send control signals to theactuators of the respective steering device 771 and brake 772 forautomatically parking the vehicle V to a desired position. The adaptivecruise control task is designed to send control signals to the actuatorsof the respective brake 772, motive power generator 773, and automatictransmission 774 for controlling the speed of the vehicle V to track atarget preceding vehicle.

Each of the task for assisting lane changes, around view displayingtask, automatic parking task, and adaptive cruise control task isperformed based on, for example, the results of the one or more imagerecognition tasks associated with

1. The lane and road-shape information

2. The preceding-vehicle and oncoming-vehicle information

3. The stopped-vehicle information

4. The preceding-pedestrian and oncoming-pedestrian information

5. The stopped-person information

6. The motor-cycle and bicycle information

7. The obstacle and roadside-object information

8. The advertising-sign and traffic-signal information

9. The traffic-marking information.

The blind-spot warning task is designed to

(1) Determine whether another vehicle is entering a blind spot at a rearcorner of the travelling vehicle V

(2) Send a control signal to the actuator of at least one of the buzzer781 and the speaker 782 when it is determined that another vehicle isentering a blind spot at a rear corner of the travelling vehicle V.

The control signal controls the actuator of at least one of the buzzer781 and the speaker 782, so that at least one of the buzzer 781 and thespeaker 782 audibly outputs a warning to occupants of the vehicle V. Thewarning represents the entrance of another vehicle into a blind spotaround the vehicle V.

The rear cross-traffic warning task is designed to

(1) Determine whether another vehicle is entering a blind spot aroundthe rear end of the vehicle V when the vehicle V is rolling backward

(2) Send a control signal to the actuator of at least one of the buzzer781 and the speaker 782 when it is determined that another vehicle isentering the blind spot around the rear end of the vehicle V.

The control signal controls the actuator of at least one of the buzzer781 and the speaker 782, so that at least one of the buzzer 781 and thespeaker 782 audibly outputs a warning to occupants of the vehicle V. Thewarning represents the entrance of another vehicle into the blind spotaround the rear end of the vehicle V.

The front cross-traffic warning task is designed to

(1) Determine whether another vehicle exists at a blind spot around thefront end of the vehicle V when the vehicle V is located at a blindintersection

(2) Send a control signal to the actuator of at least one of the buzzer781 and the speaker 782 when it is determined that another vehicleexists at the blind spot around the front end of the vehicle V.

The control signal controls the actuator of at least one of the buzzer781 and the speaker 782, so that at least one of the buzzer 781 and thespeaker 782 audibly outputs a warning to occupants of the vehicle V. Thewarning represents that another vehicle exists at the blind spot aroundthe front end of the vehicle V.

Each of the blind-spot warning task, rear cross-traffic warning task,and front cross-traffic warning task is performed based on, for example,the results of the one or more image recognition tasks associated with

1. The preceding-vehicle and oncoming-vehicle information

2. The stopped-vehicle information

3. The preceding-pedestrian and oncoming-pedestrian information

4. The stopped-person information

5. The motor-cycle and bicycle information

6. The obstacle and roadside-object information

7. The traffic-sign and traffic-signal information

8. The traffic-marking information.

The inter-vehicle distance warning task is designed to

(1) Detect an inter-vehicle distance between the vehicle V and a targetpreceding vehicle

(2) Determine whether the detected inter-vehicle distance is shorterthan a predetermined threshold distance

(3) Send a control signal to the actuator of at least one of the buzzer781 and the speaker 782 when it is determined that the detectedinter-vehicle distance is shorter than the threshold distance.

The control signal controls the actuator of at least one of the buzzer781 and the speaker 782, so that at least one of the buzzer 781 and thespeaker 782 audibly outputs a warning to occupants of the vehicle V. Thewarning represents that the inter-vehicle distance is shorter than thethreshold distance.

The rear-end collision warning task is designed to

(1) Determine whether a probability that the vehicle V will collide withthe rear end of a preceding vehicle is equal to or higher than apredetermined threshold value

(2) Send a control signal to the actuator of at least one of the buzzer781 and the speaker 782 when it is determined that the probability thatthe vehicle V will collide with the rear end of a preceding vehicle isequal to or higher than the threshold value.

The control signal controls the actuator of at least one of the buzzer781 and the speaker 782, so that at least one of the buzzer 781 and thespeaker 782 audibly outputs a warning to occupants of the vehicle V. Thewarning represents the danger of collision of the vehicle V with therear end of a preceding vehicle. Note that the inter-vehicle distancewarning task and rear-end collision warning task are performed based on,for example, the results of the one or more image recognition tasksassociated with the preceding-vehicle information.

The erroneous start preventing task is designed to determine whether anaccelerator pedal of the vehicle V is operated by a driver of thevehicle V being parked although there is a building structure in frontof the vehicle V. Note that whether the accelerator pedal of the vehicleV is operated by the driver of the vehicle V can be measured by anaccelerator sensor included in the sensor module 76. The erroneous startpreventing task is also designed to send a control signal to theactuator of the brake 772 when it is determined that the acceleratorpedal of the vehicle V is operated by the driver of the vehicle V beingparked although there is a building structure in front of the vehicle V.The control signal controls the actuator of the brake 772 to preventstart of the vehicle V due to such a driver's erroneous operation of theaccelerator pedal. The erroneous start preventing task is performedbased on, for example, the results of the one or more image recognitiontasks associated with the building structure information.

Note that the vehicle control module 77 can be configured to stop one ormore vehicle control tasks based on the actuators of target devicesassociated with motion of the vehicle V, such as the steering device 771and the brake 772, when it is determined that something blocks the viewof the camera module 3 based on the camera-view blocking info' illation.The vehicle control module 77 can be configured to stop one or morevehicle control tasks when it is determined, based on themeteorological-environment information, that it is difficult to performone or more image recognition tasks according to images picked up by thecamera module 3 due to adverse weather conditions including, forexample, torrential downpours.

As described above, the image processing circuit 79 and the vehiclecontrol module 77 implemented on the control circuit board 4 communicatewith the vehicle-side devices 75, 76, 77, and 78 via the common serialinteractive communication bus 74 communicably coupled to the devices 75,76, 77, and 78. As an exception to the configuration, the imageprocessing circuit 79 and the vehicle control module 77 implemented onthe control circuit board 4 communicate with the camera module 3 via theelectrical connection harness 5.

The image processing circuit 79 according to the embodiment isimplemented on the control circuit board 4, but the present disclosureis not limited thereto. Specifically, the image processing circuit 79according to the ninth modification can be provided at the outside ofthe imaging device 1, and configured to capture, from the imaging device1, images picked up by the imaging device 1 via the bus 74.

In the embodiment, the imaging device 1 is used, but the presentdisclosure is not limited thereto. Specifically, an optical device canbe used in place of the imaging device 1; the optical device includes atleast

1. A lens assembly (31A) including at least one lens (311 to 314) forreceiving light and a holder (32) for holding the at least one lens (311to 314)

2. A circuit board (4, 33) for perfoi ming at least one process based onthe received light;

3. A housing (2) having an opening (21) and configured to house the lensassembly (31A) and the circuit board (4, 33) therein such that at leastpart of the circuit board (4, 33) faces the lens assembly (3A), and thelens assembly (3A) is exposed via the opening (21)

4. means, i.e. a mechanism (321, 322, 323, 324) defining a passagelocated around the lens assembly (3A) to communicate with the opening(21), the passage guiding air, entering the inside of the housing (2)via the opening (21), so as not to be directed toward the circuit board(4, 33).

While the illustrative embodiment and its modifications of the presentdisclosure have been described herein, the present disclosure is notlimited to the embodiment and its modifications described herein.Specifically, the present disclosure includes any and all embodimentshaving modifications, omissions, combinations (e.g., of aspects acrossvarious embodiments), adaptations and/or alternations as would beappreciated by those in the art based on the present disclosure. Thelimitations in the claims are to be interpreted broadly based on thelanguage employed in the claims and not limited to examples described inthe present specification or during the prosecution of the application,which examples are to be construed as non-exclusive.

What is claimed is:
 1. An optical device comprising: a lens assemblycomprising at least one lens for receiving light and a holder forholding the at least one lens; a circuit board for performing at leastone process based on the received light; and a housing having an openingand configured to house the lens assembly and the circuit board therein,the lens assembly being exposed via the opening, wherein: the holder hasa substantially tubular shape; the housing surrounds at least a part ofthe holder to hold the lens assembly; and at least one of the holder andthe housing has a recess constituting a passage between the holder andan inner surface of the housing.
 2. The optical device for a vehicleaccording to claim 1, wherein the lens receives the light from theoutside of the housing through the opening of the housing.
 3. Theoptical device for a vehicle according to claim 1, wherein: the housinghas an attachment wall on a top surface thereof, the optical devicefurther comprising: a bracket for fixing the optical device to an innersurface of a windshield of the vehicle; and a thermal-conductive memberlocated between the inner surface of the windshield of the vehicle andthe attachment wall, wherein: the bracket has a top surface and arectangular opening on the top surface, and is located between theoptical device and the inner surface of the windshield of the vehicle;and the thermal-conductive member is attached to the attachment wall soas to be disposed between the attachment wall and the inner surface ofthe windshield via the rectangular opening of the bracket.
 4. Theoptical device for a vehicle according to claim 3, wherein: the innersurface of the housing has a portion that faces the passage constitutedby the recess, the portion of the inner surface of the housingcorresponding to a predetermined position of the attachment wall.
 5. Theoptical device for a vehicle according to claim 1, further comprising: ahood having a substantially V-shaped recess portion thereon; and abracket for fixing the optical device to an inner surface of awindshield of the vehicle, wherein: the housing has a first surfacelocated at a front side of the housing relative to the opening thereof;and the first surface of the housing nests the V-shaped recess portionof the hood.
 6. The optical device for a vehicle according to claim 1,wherein: the circuit board comprises at least first and second circuitboards, the first and second circuit boards being spatially apart fromeach other; the first circuit board has an image sensor for receivingthe light from the at least one lens, and is attached to the holder; andthe second circuit board has an image processing circuit connected tothe first circuit board via an electrical connection harness withoutbeing attached to the holder.
 7. The optical device for a vehicleaccording to claim 6, wherein: the lens assembly has an optical axis;the image sensor is disposed to a position of the first circuit boardsuch that the optical axis of the lens assembly passes through theposition of the first circuit board.
 8. The optical device for a vehicleaccording to claim 6, wherein: the optical device is connected to aplurality of vehicle control modules via a bus; and the second circuitboard performs an image recognition task, and outputs a result of theimage recognition task to the vehicle control modules for enabling thevehicle control modules to perform at least one of: a lane departurewarning task; a lane keeping task; a headlight control task; a task forpreventing front collisions; a task for preventing collisions atintersections; a sign displaying task; a speed-limit displaying task; anover-speed warning task; an automatic wiper task; a task for assistinglane changes; an around view displaying task; an automatic wiper task;an adaptive cruise control task; a blind-spot warning task; a rearcross-traffic warning task; a front cross-traffic warning task; aninter-vehicle distance warning task; a rear-end collision warning task;and an erroneous start preventing task.
 9. An optical device comprising:a lens assembly comprising at least one lens for receiving light and aholder for holding the at least one lens; a circuit board for performingat least one process based on the received light; a housing having anopening and configured to house the lens assembly and the circuit boardtherein, the lens assembly being exposed via the opening; and meansdefining a passage located around the lens assembly to communicate withthe opening, wherein: the holder has a substantially tubular shape; thehousing surrounds at least a part of the holder to hold the lensassembly; and the defining means is configured to define the passagebetween the holder and an inner surface of the housing.
 10. A forwardfacing camera module for a vehicle comprising: a housing, which is to befixed to an inner surface of a windshield of the vehicle; a lensassembly comprising at least one lens for receiving light and a holderfor holding the at least one lens; and a circuit board for performing atleast one process based on the received light, wherein: the housing hasa concave recess defining a space between the inner surface of thewindshield and an opening communicating with an inside of the housing;the housing houses the lens assembly and the circuit board therein suchthat the lens assembly is exposed to the space via the opening; theholder has a substantially tubular shape; a portion defining an innersurface of the opening surrounds at least part of the holder to hold thelens assembly; and at least one of the holder and the housing has arecess constituting a passage between the holder and the inner surfaceof the opening.